M18 Hellcats in Yugoslavia after WWII / the “Krajina Express”

The M18 Hellcat was an effective tank destroyer of the US Army during WWII. Its final combat use came during the 1990s collapse of Yugoslavia.

(M18 Hellcat in Cold War-era markings of the JNA, or Yugoslav Federal Army.)

(A M18 Hellcat of the Croatian army in 1994.)

(A M18 Hellcat atop the Krajina Express war train in the early 1990s.)

origin of the Hellcat

WWII American tank destroyer doctrine differed from the other warring powers. As armored tactics evolved just before WWII, the US Army observed a worrying trend, in that attacking tank units facing towed anti-tank guns emplaced line abreast could maneuver around their flanks faster than towed gun formations could reposition. What was sought was a vehicle capable of destroying a tank; but faster than a tank (and thus, less armored). The American doctrine was that “TD”s (tank destroyers) would constantly outflank an armored breakthrough, attacking the salient from its flanks and rear. TDs would be highly mobile, constantly repositioning to compensate for their weak armor.

In this strategy, TDs were specifically tasked with destroying tanks only, while light tanks would scout, and medium tanks would perform all other roles, except, paradoxically, defending against other tanks, which was to be the TD’s domain.

Fast TDs would have a gun only sufficient enough to destroy a tank, but a powerful engine and much less armor than a true tank, with the top of the turret being left open altogether. Per the theory, TDs would never face infantry.

The theory did not really work out as hoped. By the time American TDs entered serious combat on the European continent in 1944, WWII had changed. In 1940 German armored tactics stressed offensive dynamic actions with air support. By 1944, this had largely changed to semi-static defensive actions; here the advantage often went to a tank in defilade that got the first shot off against a moving foe, even if the latter was faster and more nimble.

Despite the shortcomings in doctrine, the M18 Hellcat itself was a successful vehicle. During WWII it had a 2.3 : 1 kill-to-loss ratio.

(M18 Hellcat receiving tracks at the Buick factory during WWII.)

The USSR’s success with the T-34 on the eastern front served as the template for what would become the MBT (main battle tank) precept of the Cold War, making the USA’s pre-WWII TD tactics redundant.

Two months after Japan surrendered, the US Army ceased promulgating TD tactics effectively killing the concept, and dedicated tank destroyer battalions were disbanded. The Hellcats themselves were still high-quality vehicles, and were reassigned to other units (later seeing combat in Korea) or exported.

(During and after WWII, a total of 640 US Army M18 Hellcats were rebuilt into M39 armored vehicles. As the baseline tank destroyer version became obsolete, these were the last versions of the WWII vehicle in American service after the Korean War, being used in the development of the M59 and M113 APCs of the Vietnam War era. The last was retired in 1957.)

M18 Hellcat: basic description

The United States fielded three TDs during WWII; the M10 Wolverine, the M36 Jackson, and the M18 Hellcat. Of the three, the Hellcat had the smallest gun and weakest armor, but was by far the fastest.

(US Army M18 Hellcat during WWII.)

The M18 had a 5-man crew: the driver and “co-driver” in the hull front, and the commander, loader, and gunner in the open turret. The vehicle was 17’4″ long less the gun, 9’4″ wide, and 8’4″ tall with 1’2″ ground clearance. The combat weight was 19½ tons.

(Close-up of the mantlet, which was the thickest armor on the M18 Hellcat. The D-rings were for lifting the turret off the chassis for maintenance.) (photo by David Lueck)

The main gun was a M1A1 or M1A2 76mm weapon (2,600fps muzzle velocity). At a 30° impact the standard M79 AP round could penetrate 4¼” of common steel at 500yds and the HVAP-T (high velocity armor piercing tracer) round, the M93A1, 6″ at the same range. The HVAP-T maintained its velocity over longer ranges and was still rated to 5″ of steel at over half a mile.

(Diagram of the WWII M93A1 ammunition from a Cold War-era JNA handbook.)

(A M93A1 round being handled for the M18 Hellcat on the Krajina Express war train during the 1990s.)

The Hellcat carried 45 rounds, 9 of which were in a ready box next to the breech. The open-top turret traversed hydraulically at 24°/second. The turret also had a M2HB Browning .50cal machine gun with 800rds.

The welded hull had only ½” thick armor. The front of the turret was ¾”, the gun mantle 1″, and the sides of the turret ½”.

The powerplant was a Continental R-975 radial 9-cylinder gasoline engine with 3F/1R Toqrmatic transmission. The engine was in the vehicle rear and the transmission between the driver and co-driver up front. The tracks were rubber-bushed T69 steel type.

The Hellcat was not only fast, it was extremely fast. On pavement the top speed was 51mph, and off-road 21mph – 28mph was common. By comparison a Hellcat was faster in a foot of snow over mud, than a Panzer IV was on the autobahn.

By the time Yugoslavia received Hellcats, they were obsolete in their intended role due to their meager armor and small (by 1950s standards) gun. Their speed and agility were no longer viewed as acceptable substitutes for either. But one advantage the Hellcat kept was weight. In the immediate post-WWII world, it was 12 tons lighter than a M4 Sherman and 7 tons lighter than a T-34. As years passed this disparity increased – three decades after WWII, the Yugoslav Hellcats were 23 tons lighter than both T-72s to the east and Leopard Is to the west. Why this mattered is that in the 1970s, 1980s, and (as was proven) in the 1990s, they could use bridges, roads, and other infrastructure unsuitable for heavier tanks.

The official nomenclature was “Gun Motor Carriage, M18”. The USA planned to build 7,386 plus another 1,600 for possible Lend-Lease. However because of the issues mentioned earlier only 2,507 were made, the last in October 1944. Each cost $55,230 or $780,000 in 2020 dollars.

M18s to Yugoslavia

In 1950, an agreement was signed whereby the United States would sell certain ex-Wehrmacht items and surplus WWII US Army gear stored in the former American occupation zone of Germany to Yugoslavia. This came during the interval after West Germany regained sovereignty in 1949 but before it remilitarized in 1955. The goods in question were a bric-a-brac of WWII items warehoused since 1945, now of mediocre future value to any NATO army. However the Yugoslav Federal Army (its Serbian acronym, JNA) still was making widespread use of ex-Wehrmacht equipment and Lend-Leased American kit, so it would be of significant value to them. Besides the small cash benefit, it rid the USA of the hassle of guarding the gear.

(An ex-Wehrmacht StuG III tank destroyer operated by Yugoslavia during the late 1940s. Some served into the 1950s.)

This sale went fine and was pleasing to both sides. In May 1951, the JNA’s Chief Of Staff, Gen. Koce Popovica, visited the Pentagon and made a case for Yugoslavia becoming eligible for MDAP (Mutual Defense Assistance Program) aid. MDAP had become American law in October 1949, and was intended to provide allies with leftover American WWII weapons at low or no cost. Yugoslavia was considered remarkable for MDAP eligibility, in that it was the first recipient not in any formal defense agreement with the United States, and the first (and as it turned out, the last) communist MDAP country.

(A JNA exercise during 1953. All of the equipment is of WWII origin; the M4 Sherman tanks being obtained from the United States via MDAP. The stahlhelm M35 helmets were either left behind by the Germans during WWII or bought via the 1950 American deal. The German 98k rifles were designated M98 in their WWII condition, M98/48 if refurbished, and M48 for new rifles made on surrendered German production jigs.)

Under MDAP, Yugoslavia ordered 150 M18 Hellcats in 1951. These were delivered during 1952. An additional 90 M18s followed in smaller batches, for a total of 240 by the start of 1955 when the JNA’s procurement was completed.

(JNA soldiers lay a tarp over a M18 Hellcat during an exercise.)

In service, JNA Hellcats were considered self-propelled anti-tank artillery and organized into subunits for armored or infantry divisions. The official Yugoslav nomenclature was “SO-76 Helket”.

(Yugoslavia also obtained 415 WWII M36 Jackson tank destroyers through MDAP. This 1950s JNA exercise shows a Yugoslav Jackson along with infantry still wearing stahlhelms.)

(Yugoslavia also looked east for WWII-surplus tank destroyers and bought SU-100s from the Soviet Union. The Soviets considered these “assault gun vehicles” and their concept was markedly different than the USA’s during WWII. This one was participating in a 1971 Yugoslav amphibious exercise.)

During the early part of the Cold War, the M18 Hellcat was considered a satisfactory mobile anti-tank asset by the JNA, if less powerful than the M36 Jacksons. Throughout the 1950s the expected opposition would be M4 Shermans of NATO countries or T-34s of the Warsaw Pact. In either case the M93A1 round was considered sufficient under the right circumstances. The Hellcat’s own armor was already insufficient against lesser tanks during WWII, so its inadequacy in direct encounters against tanks was already accepted as a given.

(Yugoslav M18 Hellcat in service. The JNA preferred to install the M2HB Browning .50cal’s optional flash hider whenever possible. The U-rings on the turret side were to install a rain tarp. The crew’s helmets are WWII Soviet “three-pad” style which were both bought from the USSR and license-made in Yugoslavia.) (photo via Dimitri Jeostojic)

By the 1960s, NATO armies were fielding the M48 Patton with the US Army introducing the M60. Meanwhile while there were still significant numbers of WWII T-34s in the Warsaw Pact, the T-54/55 was now the standard combloc tank (Yugoslavia also used the T-54/55). Against these tanks, the Hellcat’s WWII 76mm gun was of declining effectiveness.

(This 1963 CIA assessment of the JNA showed 220 of the original 240 Hellcats still in service at that time. There were still 370 Jacksons as well. Of other interest is the surprising amount of ex-Wehrmacht gear still in Yugoslav use two decades after WWII, including 140 of the famous 88mm FlaK 36/37 gun. This document was declassified in 2006.)

By the 1970s, the ageing Hellcats were starting to have mechanical problems, including frequent ignition failures. At the same time, their niche in the JNA was now being filled by ATGMs (anti-tank guided missiles) purchased from the Soviet Union. The M18 Hellcats began to be withdrawn from frontline JNA service.

Yugoslavia reassigned still-serviceable Hellcats to the Teritorijalna Odbrana (Territorial Forces), a sort of second-tier army. The country as a whole maintained a central TO, and additionally each of the six constituent republics had their own separate smaller TOs. Notably during the Cold War, there were repeated calls to disband the republic’s own TOs due to fears they could someday form the cores of secessionist armies. The disbandment was never done and in the cases of Slovenia, Croatia, and Bosnia-Herzegovina; to an extent that was exactly what happened.

(This 1990 American assessment of the JNA, the final one before Yugoslavia began to fall apart, shows the M18 Hellcat completely out of frontline military service; all having gone to the TO or discarded altogether. However there were still 250 WWII T-34 tanks in frontline JNA service.)

M18 Hellcats were still active in TO drills and periodic exercises through the late 1980s. By then, they were completely obsolete in their original WWII mission however they were still considered a moderately effective mobile infantry support asset, capable of taking out APCs or enemy fortifications. Their final niche was usually described as “long-range support”; backing up foot infantry at the extreme forward edge of the battle area.

the breakup of Yugoslavia

The violent dissolution of Yugoslavia is well known and outside the scope of this writing. In summary, during the 1950s, 1960s, and 1970s; Yugoslavia enjoyed tremendous economic growth and its citizens enjoyed a standard of living comparable to the USA or France, and light years ahead of the rest of eastern Europe including the Soviet Union.

However by the 1980s, difficulty in servicing the country’s large foreign debt (largely denominated in American dollars and West German marks, both rising relative to the Yugoslav dinar) stagnated the economy. The death of longtime leader Tito in May 1980 removed a “glue” that held the political center together and increasingly Yugoslav politics took on a nationalistic tone, with leaders of the constituent republics seeking decentralization. This started a snowball effect, where the federal system became erratic and ineffective, leading to more decentralization, and so on.

(This hypothetical scenario was prepared by the CIA for President Nixon in 1971. It is quite eerily accurate in what happened decades later with the exception of Soviet support, as the USSR itself would end in 1991. This document was declassified in 2006.)

In June 1991, Slovenia declared independence, followed by a 10-day conflict between the former Slovene republic’s TO and the JNA. The latter was hobbled by the fact that at the same time, tensions were already simmering in the Croat republic, so the JNA (which was quickly devolving into a de facto army of Serbia) was essentially fighting a war two republics removed from its “home area”. There was also, frankly, not a lot of urgency felt in the Serb, Montenegrin, and Macedonian republics to keeping Slovenia in the union.

M18 Hellcats were present in the Slovene republic’s TO prior to the conflict but it is not thought that they played any appreciable part in the 10 days of fighting.

The heaviest fighting began when the Croat and Bosnia-Herzegovinian republics declared independence. In Croatia the rapidly-unraveling federal army, the JNA, had only partially seized the assets of that republic’s TO. What was not seized generally ended up in Croat militias that formed the nucleus of the later Croatian army, or to the self-styled Serb statelet known as Krajina.

Krajina was actually three separate ethnic-Serb enclaves in Croatia: one on the Dalmatian coast and another in south-central Croatia; these both abutting Republik Srpska (the ethnic Serb statelet in Bosnia); plus a third disconnected region far east.

Prior to 1991, constituent republic borders inside Yugoslavia were basically administrative lines on a map and were not intended to ever function as hard international borders. The secession of Croatia resulted in Serbs on the “wrong” side of the new border becoming marooned in a foreign land, which they viewed as unacceptable. Meanwhile Krajina’s existence would result in Croatia effectively being bisected, which was equally unacceptable to them. Thus it is not hard to see how the conflict started.

Both sides used M18 Hellcats during the fighting.

(Croatian Hellcat in 1994. For all sides in the war, it was common to see tanks carrying a mixture of leftover JNA numbers plus new national insignia; the latter usually painted by hand.)

(Serb-operated M18 Hellcat.)

(A Croatian M18 Hellcat embarks onto a civilian river ferry during 1994. Compared to Cold War-era tanks, the WWII Hellcat’s light weight enabled it to use much lighter transportation infrastructure.)

The secession of Bosnia-Herzegovina, and the resulting conflict, was a much messier affair both politically and militarily. Inside Yugoslavia, the Bosnian republic had no real “native” majority; with the population split along muslim Bosniak and ethnic Croat and ethnic Serb lines. Of these, the first two formed a tenuous Federation (which sometimes broke down), while the Serbs created their own statelet, Republik Srpska.

(The final front lines at the end of the conflict. These changed much throughout the early 1990s, with Serb control at times extending much deeper in the northwest.)

In particular the borders of Srpska abutted Serbia proper, and also in many places, the Serb self-styled Krajina republic inside Croatia; and cross-border movements and coordination were common. The Bosnian war, itself vicious, was thus intensified as at times it became an extension of fighting inside Croatia.

Just as had happened in Slovenia and Croatia, the earliest version of the muslim Bosniak army was formed around the area’s former TO, and in fact, from 1991 – 1992, simply called itself “Teritorijalna Odbrana Bosne-i-Hercegovine”.

Names aside, by now the remaining JNA – at this point now Serbia’s de facto army – had learned it’s lesson and had taken all available steps to seize the Bosnian republic’s TO’s gear as Bosnia-Herzegovina became independent. Therefore far less WWII-era gear was initially available at the outset; this counteracted by a larger seizure of modern frontline JNA gear stuck inside the new country’s boundaries. The flip side of this was that JNA units withdrawing into Serbia proper were usually sympathetic to the local Serb cause, and unofficially saw to it that seized TO gear was redistributed to local Srpska militias.

(A M18 Hellcat of the Srpska army in action near the city of Brcko. This strategic city abuts the Bosnia-Croatia border and formed the “hinge” between the two “jaws” of Republik Srpska.)

(A Republik Srpska M18 Hellcat somewhere on the Bosnian front. This photo shows the driver and co-driver’s WWII periscopes on the inside of their hatches.)

(This Serb-manned M18 Hellcat was taking part in the siege of Gorazde. This city on the Drina river, overwhelmingly Bosniak, was isolated deep inside territory that was otherwise overwhelmingly Serb. From 1991 – 1995, Srpska forces besieged it but never managed to overrun it. This particular Hellcat survives today in 2020 as a memorial, repainted but with it’s turret still pointed as shown.)

(In December 1992, Federation forces mounted a major offensive (operation “Circle”) to lift the siege of Gorazde. They succeeded in doing so for about a week before the offensive petered out. During this operation, a good amount of Republik Srpska gear was captured intact, including two M18 Hellcats. This one was taken at the nearby village of Obadi. Vehicles changing hands was not uncommon during the Bosnian War; some were captured multiple times.)

(This Serb-manned M18 Hellcat is almost completely encased in ad hoc “rubber armor”, the function and nature of which is described further below. This was not at all uncommon in a bid to increase the protection of WWII-era vehicles against modern HEAT warhead ordnance. Besides M18 Hellcats, it was widely seen on WWII-era T-34 tanks and M36 Jackson tank destroyers during the 1990s breakup of Yugoslavia.)

(This Republik Srpska M18 Hellcat shows makeshift mounting frames used to drape “rubber armor” around the turret.)

The M18 Hellcats were not the only WWII tank destroyers to see combat in Bosnia-Herzegovina during the 1990s. Below are a SU-100 and a M36 Jackson used by Serb fighters.

(photo via oklop2.tripod.com website)

Frankenstein Hellcats on the Bosnian front

For all three sides fighting the war, it was an “adapt and make-do” affair as the international community tried (and, all things considered, largely succeeded) blocking fresh arms shipments to the warring parties. Several of the WWII-era Hellcats were strangely modified and became famous in their own right. This was due to both damage and to a lack of spare parts for the WWII vehicles which, by then, had been out of production for 50 years.

The Republik Srpska M18 Hellcat below was massively modified by completely removing the WWII engine and entire rear deck, and replacing it with an engine (along with the radiator, starter, grille, and even hood!) of a civilian FAP-13 truck.

For comparison’s sake, a normal FAP-13:

This engine was rated at 130hp compared to the WWII Continental engine’s 350hp, so it is unknown how efficient this set-up was or if it even worked at all. It possibly did, as when the conflict ended another M18 Hellcat turned over to peacekeepers had it’s engine gutted, maybe in preparation for a similar “surgery”.

On the Bosniak side, there was also supposedly a M18 Hellcat successfully re-engined with a commercial Deutz diesel imported from Germany.

Even more dramatic was the “half-breed” M18 Hellcat – T-54/55.

This vehicle started lift as a normal JNA T-54/55 Cold War-era tank. In 1991 it was passed, legally or otherwise, by the withdrawing JNA to a local Serb militia in Bosnia. Shortly thereafter, it was “mobility-killed” (most likely either track damage or superficial engine damage) by Bosniak forces and abandoned otherwise intact.

Bosniak troops repaired it and added it to their army. During 1992 a Serb ATGM team scored a devastating hit on the T-54/55’s turret. After the battle an inspection revealed that while the ATGM had obliterated the turret, the “lower” part of the tank was relatively undamaged and in fact, even still could be driven.

The lower portion was taken in and cleaned up by Serb mechanics. The turret from a M18 Hellcat was installed via a custom-crafted adapter ring seated inside the original lower turret ring of the Soviet-made tank.

This “half-breed” served in the Srpska army for about a year, until it became mired in mud and was abandoned by it’s crew. (This was not uncommon during the 1990s fighting as wreckers were not always readily available to the fighting parties.)

Discovered by Bosniak troops, it was recovered and changed hands yet again, successfully serving in the Federation army for the remainder of the war.

Above is the vehicle in the final camouflage scheme, with the Bosnian fleur-de-lis insignia on the glacis.

the Krajina Express

War trains are certainly not a novel creation of the 1990s Yugoslav wars, having existed in various forms since at least the USA’s 1861 – 1865 civil war. In the Balkans, they existed during and even after WWII.

(A railcar-mounted Panzer IV used by the Wehrmacht in occupied Yugoslavia during WWII.)

(A post-WWII Yugoslav war train car, this one mounting the 47mm turret of a WWII Italian Ansaldo M15/42 tank. The JNA operated war trains of various styles from 1946 – 1957.)

By the 1990s, the era of war trains was largely viewed to be yesterday’s history. Expensive to run in either peacetime or war, they are obviously restricted to the route of railroad tracks, and highly vulnerable to air attack. Possibly the last time a war train would become famous was the “Krajina Express” of the 1990s.

The Krajina Express was first created during the summer of 1991 by ethnic Serb railway workers in the city of Knin, today in Croatia’s Dalmatian coast inland east from the city of Zadar and about 13 miles west of the present Croatian-Bosnian border. In 1991, Knin was inside the Serb statelet of Krajina (for a while it was the self-proclaimed “capital city”), and possessed a railway service depot of the former Yugoslav Railways. The “beating heart” of the Krajina Express was a JZ664 civilian locomotive. This mighty machine was built in Yugoslavia between the early 1970s – early 1980s and was powered by a General Motors EMD 2,168hp V-16 diesel.

(An example of a JZ664.)

The locomotive was not intended to be a fighting car, only the power. For combat a variety of railcars were built. The number, configuration, and weapons fit of these changed several times during the Krajina Express’s life; but always included at least some WWII-era armament.

the first modification

The first (1991) iteration of the Krajina Express had the locomotive, two passenger cabin cars behind it, and two modified flatbed cars ahead of it. On this version, the “lead” car (obviously the whole train could move in either direction) was armed with a WWII German FlaK 38 twin 20mm anti-aircraft gun. In post-WWII Yugoslav nomenclature, these surrendered weapons were called PA M38.

(The FlaK 38 in it’s original German WWII single-barrel, heavy towed mount configuration.) (official US Army photo)

(After WWII Yugoslavia remounted these German guns onto lightweight twin-barrel towed pedestals as shown, designated PA M38.)

(The 1965 edition of the PA M38’s operator manual. These WWII guns were still in frontline JNA service then, but later relegated to the TO.)

(The PA M38 aboard the Krajina Express firing in 1991. This might have been during the war train’s first combat use, clearing the area adjacent to the rail line between Knin and Drnis.) (image via RTS Serbia)

The car behind it carried two Soviet-made, Cold War-era AT-3 “Sagger” guided anti-tank missiles and a WWII British 40mm Bofors AA gun, which was referred to by the JNA as the M12. On this first version of the train, the two combat cars were protected only by sandbags and makeshift sheet metal enclosures. The passenger cars were not intended for fighting, only for the crew to live in. They were not always towed along.

Towards the end of 1991, the train participated in the defense of the former Yugoslav airbase at Zemunik near Zadar, Croatia. It was also during this time that the train gained its nickname. The Krajina Express was officially “7th Armored Train” which was almost never used.

the second modification

The next (1992) iteration of the Krajina Express changed the combat car fit and protection level. The locomotive was enclosed in 25mm steel armor.

(The up-armored locomotive.)

The “lead” car’s gun fit was changed. The WWII German 20mm gun was removed and replaced with a WWII Soviet ZiS-3 anti-tank gun, which was designated M42 in the JNA nomenclature system.

(ZiS-3 fitted to the Krajina Express.)

The ZiS-3 was a successful anti-tank gun of WWII, with over 103,000 being made. It fired a 76.2x385mm(R) AP cartridge that could penetrate 2¼” of 60°-sloped hardened steel at 575yds. After production ended with Germany’s 1945 defeat, the USSR exported the weapon widely, including to Yugoslavia.

(At the end of the Bosnian War in 1996, Republik Srpska troops turned over this WWII towed ZiS-3 to the US Army 1st Cavalry Division.)

Much like the M18 Hellcat, by the 1980s the ZiS-3 was obsolete in it’s WWII role as it would have little chance against a M1 Abrams or T-72. None the less, again like the Hellcat, it retained usefulness as an infantry support weapon and was passed on to the TOs. The particular ZiS-3 fitted to the Krajina Express had originally been allocated to the Croat federal republic’s TO and was seized out of a storage armory by ethnic Serbs in Croatia when the fighting started.

An additional combat car was added. It carried no WWII arms but entirely modern weaponry, a M55 triple-barrel AA gun and a M75 20mm autocannon. It was placed in the “second” position.

The original “second” combat car was now placed “third”, closest to the locomotive. It received additional steel armor, and a Browning M2HB .50cal machine gun.

(The beefed-up 40mm car, showing also the added WWII Ma Deuce plus the two missiles which were obviously not of WWII origin.)

In this configuration, the Krajina Express was used only sparingly as the war train’s crew was also standard infantry and for much of 1992 was fighting on the ground during the “Koridor” operation.

During early 1993, the Krajina Express undertook a remarkable operation which might be more at home in a fictional “wild west” cowboy movie than actual late-20th Century warfare.

Serb forces received intelligence that Croat forces were using a railway tunnel near Zadar as an ammo dump to shield the munitions from airstrikes or artillery. (The railroad itself was blocked by the frontlines both east and west of the city.)

A boxcar was packed full of 4 tons of high explosives and a similar amount of scrap metal to act as shrapnel. On the front of the car, a “bumper” of anti-tank mines set sideways would serve as a detonator, backed up by a crude timer inside the car. The Serb plan was to have the Krajina Express push this “railbomb” detached at high speed just past the town of Nadin (about 8 miles from downtown Zadar) and then slam on the brakes about 23,000′ ahead of a Croat pillbox defending the tunnel, sending the “railbomb” careening down the tracks onwards. The Krajina Express would then travel in reverse back to Serb-held territory.

The release went as planned and the train’s crew heard a tremendous explosion, as did Croat civilians in Zadar, however the ammo dump was not destroyed. It is still not clear what if anything was hit.

the third modification

The final (summer of 1993) iteration was the longest-lasting, most used, and easily the most-photographed and most famous build of the Krajina Express; and also the one with the M18 Hellcat.

The armor on all three cars plus the locomotive was greatly improved, both with additional steel and with “rubber armor”. This “rubber armor” was sheets of processed material, not spongy rubber but rather similar to what one might find in a supermarket check-out’s conveyor belt. Against HE, AP-sabot, or solid-core AP ammunition, it was utterly useless. However against HEAT ammunition it was marginally effective as it was rigid enough to pre-detonate a HEAT warhead so that the molten slug was already starting to dissipate by the time it reached solid armor. At the same time, it was pliable enough that sometimes the incoming weapon would get thrown off-axis causing the molten slug to strike the main armor at an undesirable angle.

(The second and third cars plus the rear of the first car and the locomotive, showing the sheets of “rubber armor”.)

This so-called “rubber armor” was used extensively by all sides during the breakup of Yugoslavia on WWII legacy vehicles to add a bit of protection against Cold War-era HEAT weapons like the RPG-7 or “Sagger” missile. Aboard the Krajina Express, more protection came from crushed mica which was poured into the gap between the rubber and the solid steel armor, forming a crude compound effect. The mica’s additional weight was irrelevant as unlike a land vehicle such as a T-34, the train did not need to worry about ground pressure and the locomotive put out way more horsepower than would ever be needed regardless. This “rubber armor” apparently worked good enough as the Krajina Express was hit by at least three HEAT weapons (RPGs, recoilless rifles, or ATGMs) but was undamaged.

In this final iteration of the train, the first car was completely rebuilt. The new centerpiece was an entire WWII M18 Hellcat, placed in the front.

It is unknown if this Hellcat was mechanically operational or not, but in the end it doesn’t really matter as it would never move by itself again. The WWII .50cal AA mount was left in place. The WWII turret and main gun were fully operational.

(Loading ammunition into the ready-use box next to the Hellcat’s main gun breech. The Hellcat aboard the Krajina Express was colored like most Yugoslav ones by the start of the 1990s…five decades’ worth of peeling paint layers plus rust. The stump in the lower right corner is where the WWII radio’s antenna was once mounted.)

(The new first car, seen here detached from the rest of the Krajina Express.)

Behind the M18 Hellcat on the refit first car were two non-WWII weapons,  pair of L57-12 air-to-ground rocket launchers. This Yugoslav system was for Cold War-era combat aircraft and fired volleys of unguided rockets. There was no real way to “aim” these weapons in a surface-to-surface role other than calculating a crude ballistic arc with tabletop math; but wherever the rockets did happen to land received a terrible pounding.

The second and third cars received the same new armor package as the first, but did not have their weapons fit changed.

(The entire Krajina Express in 1994, showing the embarked Hellcat.)

The fit of the WWII-vintage Hellcat onto the war train was successful and put a hard-hitting asset at the front; capable of taking out light APCs or houses being used as bunkers along the railroad.

(The Hellcat’s AA Browning M2HB .50cal retained the optional WWII flash-hider, as did most Yugoslav examples. Contrary to the public perception this does not “conceal” the machine gun’s muzzle flash from the enemy but rather, makes it less disorienting to the gunner. There was no air opposition to the train so it was used in a ground-to-ground role.)

In this final iteration of the Krajina Express, the two passenger cars were carried behind the locomotive, and now in front of the first combat car (the one with the Hellcat), two or three plain unmodified flatbeds were attached. They carried railroad supplies and tools to repair sabotaged tracks (as the Krajina Express’s fame grew, so did this issue), and also would set off tiltrod mines laid on the railroad rather than the combat car with the Hellcat and crew.

Despite its nickname, the Krajina Express spent probably as much time outside of Krajina as in it. In particular, it fought in western and north-western Bosnia-Herzegovina, especially in the Bihac area.

All in all, the Krajina Express was remarkable in numerous ways; the first being that it even existed. Beyond that the pairing of WWII-era and Cold War-era systems was notable, and just the engineering skills required to make the contraption work.

(The height and width of the Krajina Express was limited by max clearances of civilian Yugoslav Railways tunnels and bridge trestles.)

(The Serb designers also ensured that the combat cars could negotiate any track curve in the war train’s expected operational area.)

the end

The Krajina Express was used extensively throughout the latter part of 1993 and all of 1994, up to the start of December. The train was so busy that in fact it had two crews, much like a modern naval ballistic missile submarine, keeping the train in action for the maximum amount of time while one crew rested.

During the early part of 1995 battlefield setbacks resulted in greater difficulty in finding enough friendly “points A and B” connected by rail. The city of Knin, the train’s birthplace, fell to the Croatian army during the first week of August 1995. Soon the entire ethnic-Serb Krajina statelet would be overrun. The last missions were to evacuate friendly troops and civilians from the Dalmatian interior to Republik Srpska inside Bosnia. The Krajina Express’s crew did not want the war train to be captured intact, so it was decided to destroy it. A curved section of track on a steep incline was identified, and the three combat cars were detached from the locomotive, and then pushed off at high speed causing their derailment in a rocky ravine.

The locomotive, the only surviving part of the train, was abandoned. It was captured intact by advancing Croatian troops. After the end of the war, it was “un-modified” back to its original civilian appearance and allocated to HZ Railroad in Croatia.

(The former Krajina Express’s locomotive in 2012.)

As of 2020 it is still in service, HZ # 2-062-055. It is not specially marked and outside of railroad enthusiasts and HZ employees, probably nobody in Croatia would recognize it as having been part of a remarkable military spectacle which fought against their country decades ago now.

The Krajina Express’s former crew is now spread around the world, some in Serbia; others having moved elsewhere in Europe or to the USA. Despite the train’s onetime fame former crewmen rarely speak in public of the Krajina Express.

It seems doubtful that such a system will ever be seen again anywhere in the world. By 2020, there are far fewer WWII weapons still circulating than there were in 1991. The circumstances which allowed this war train to operate were specific and might seem hard to duplicate elsewhere……before it split apart, Yugoslavia had one of the best railroad networks on Earth; the train itself was never subjected to air attack; and the unusual nature of the Krajina and Bosnian wars battlefields – an array of isolated exclaves and this corridors to be gained and defended – might not be repeatable elsewhere.

(The unofficial emblem of the Krajina Express.)

postscript

The first round of fighting in 1990s Yugoslavia (the secession of Slovenia and then the Croatian and Bosnian Wars) ended with the Dayton Agreement of late 1995 that entered force the following year. Of any M18 Hellcats still operational, Croatia used a handful during the late 1990s before their retirement. The Republic Srpska Hellcats were generally turned over to international peacekeepers. Serbia proper (which at that time was still in union with Montenegro and still referring to itself as a rump Yugoslavia) did not further use M18 Hellcats, although it kept some SU-100s and M36 Jacksons running to the turn of the millennium.

(Discarded Croatian army M18 Hellcats in an open-air museum near Karlovac.)

During the second round of Yugoslav fighting (the 1999 NATO air war and then then debridement of Kosovo from Serbia) no Hellcats were used but inoperable hulks were used as decoys to deceive NATO warplanes. WWII M4 Sherman hulks were also successfully employed for the same purpose.

(M18 Hellcat with the US Army in Europe during WWII, and a half-century later, with the Republik Srpska army.)

 

 

 

 

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