A brand-new example of the 10.5 cm leFH 18/3 auf Geschützwagen B2 self-propelled gun — note the tarpaulin stretched over the open fighting compartment, source: Flickr.com, with permission of the publishing user, edited

French War Booty

Following the French capitulation in June 1940, the Germans laid their hands on an enormous haul of war materiel. This included, among other things, thousands of armoured fighting vehicles of every description — among them 161 heavy Char B1 bis "breakthrough" tanks. This was a type that had been in development since the early 1920s, designed to break through strongly fortified enemy lines. The vehicle carried two artillery weapons: a 75 mm gun mounted in the hull front for destroying enemy fortifications, and a 47 mm gun in a rotating turret for dealing with enemy armour. The French designers had also given the tank a very solid frontal armour of 60 mm. Unfortunately, the development process had taken so long that the vehicle's overall concept and technical execution were substantially obsolete before series production could even begin. French army representatives either failed to see this or simply chose not to — how else to explain the fact that they ordered an astonishing 1,144 of these behemoths? By the time of the German attack on France, the army had managed to take delivery of "only" 369 of them.

For German tanks, this heavily armoured vehicle was a genuinely tough nut to crack — yet the French lost enormous numbers of them through their own mistakes, particularly poor logistics. Crews frequently abandoned or blew up their vehicles simply because they had run out of fuel or ammunition. The captured vehicles were taken into German service under the designation Panzerkampfwagen B2 740(f), though the Germans were not especially enthusiastic about them. The Char B1 bis was relatively slow, its fighting turret had room for only one man, the hull-mounted 75 mm gun could only traverse one degree to either side (which severely limited its practical usefulness), and the turret gun lacked any exceptional destructive power. In short, the Germans saw no sensible combat role for these tanks in their army — at least not in their original form. It did occur to them, however, that these vehicles might prove more valuable in other roles.

German Conversions

In March 1941, a decision was therefore made to carry out two distinct conversions of this captured tank into "something else". The first was a conversion into a flame-thrower tank capable of clearing bunkers and field fortifications of concealed infantry. The second conversion was a self-propelled gun intended to accompany the flame-thrower tanks on the battlefield and provide them with fire support. It is naturally this second conversion — the self-propelled gun — that concerns us in this article. The Ordnance Office entrusted the development of this conversion of the original French Char B1 bis to the firm Rheinmetall-Borsig, with the requirement that the first prototype be ready by June 1941.

Individual self-propelled guns were rather unusually identified by large letters painted on the sides of the fighting compartments, source: Flickr.com, with permission of the publishing user, edited

Exactly when Rheinmetall-Borsig delivered a detailed design for the required vehicle is not clear from the available literature, but it is certain that it was not early enough for production to begin before the invasion of the USSR. The German flame-thrower tanks built on the French Char B1 bis chassis (designated PzKpfw B2 (Flamm)) therefore had to go into action on 22 June 1941 without their intended artillery escort. The very first deployment of these flame-thrower tanks against the so-called Molotov Line revealed serious technical problems, and all surviving vehicles were quickly withdrawn from the front — which apparently also brought a halt to further development of the self-propelled gun on the same chassis, at least for a time.

Development of the PzKpfw B2 (Flamm) flame-thrower tank continued, and in November 1941 the Wehrmacht took delivery of the first examples of its improved "production" variant. This most likely revived work on the self-propelled gun on the same ex-French chassis — though reportedly this time no longer under Rheinmetall-Borsig, but under the firm Alkett. However it all played out, in January 1942 the army was able to take delivery of the first five brand-new 105 mm self-propelled guns, designated 10.5 cm leFH 18/3 (Sf.) auf Geschützwagen B2. Five more followed in February and the final six in March 1942.

Design Description

The conversion of the French tank into a self-propelled gun was fairly straightforward. The 75 mm hull gun was removed and the opening in the front plate was blanked off with a piece of armour. The original fighting turret was also removed, and in its place a tall fixed superstructure appeared, enclosing the newly created fighting compartment. The walls of this superstructure were 30 to 40 mm thick at the front and 20 to 30 mm on the sides and rear — genuinely generous protection given the vehicle's intended role, since the self-propelled gun was not meant to engage the enemy directly but to provide fire support from a degree of "safe" distance. The roof of the superstructure was left open, which made aiming easier, improved ventilation and allowed freer movement and easier ammunition handling within the fighting compartment. The corresponding section of the tank hull roof was most likely also modified to serve as the floor of the new fighting space.

A 10.5 cm leFH 18/3 auf Geschützwagen B2, probably in the courtyard of the 26th Panzer Division's barracks in France, source: Flickr.com, with permission of the publishing user, edited

Inside the fighting compartment the 105 mm leFH 18/3 light howitzer was installed. The front wall of the fighting cabin was formed by a two-part movable gun shield connected to the barrel. The larger section of the shield maintained the integrity of the armour protection as the gun traversed horizontally, while the smaller section did the same during vertical movement of the barrel. Horizontal traverse was 14 degrees to each side; vertical elevation ranged from -5° to +20°. The howitzer used separate-loading ammunition, meaning the shell was rammed first followed by the cartridge with its propellant charge. The range could be adjusted by varying the size of the propellant charge — that is, the number of powder bags inserted into the cartridge, with six charge sizes available on the standard towed leFH 18, the largest of which gave a range of around 10,675 metres. It is quite possible that on the self-propelled variant the use of the heaviest charge was prohibited (this was not unusual practice). The standard 105 mm high-explosive fragmentation shell weighed 14.81 kg, of which 1.38 kg was the TNT filling. How many rounds of artillery ammunition could be carried aboard the self-propelled gun is unfortunately not known from the available sources.

The 10.5 cm leFH 18/3 (Sf.) auf Geschützwagen B2 self-propelled howitzer weighed 32.5 tonnes — a full tonne more than the original French Char B1 bis tank. Compared to the tank, however, both the length and height also increased. The overall length of the self-propelled gun was 762 cm, against 637 cm for the original tank — the entire increase being accounted for by the gun barrel projecting beyond the hull outline. The vehicle's height rose from 279 cm on the original tank to an even 300 cm on the self-propelled howitzer. An already tall vehicle thus became taller still, and consequently a more conspicuous target. The remaining dimensions of the self-propelled gun stayed more or less the same as those of the ex-French tank: width 246 cm, maximum speed approximately 25 km/h, a Renault engine producing 309 horsepower, a five-speed gearbox, and fuel tanks with a combined capacity of 400 litres.

The crew of the self-propelled gun consisted of five men: driver, commander, gunner and two loaders. Neither sources nor photographs make it clear whether the fighting cabin had any access door in its rear wall. If not, crew members most likely entered through a hatch in the floor — that is, from the hull below (which was itself accessed via an entry hatch in the right side of the hull). It was of course also perfectly possible to simply climb over the compartment walls, though at three metres above the ground that seems better suited to an emergency than routine practice. The crew could shelter from bad weather by pulling a waterproof cover over the fighting compartment, secured by straps to loops on the side walls. For communication, the vehicle carried an Fu.5 radio set with a whip antenna.

Soldiers in Italian uniforms inspecting the 10.5 cm leFH 18/3 auf Geschützwagen B2 self-propelled gun — the photograph may have been taken in Sardinia after the vehicles were transferred to the 90th Panzer-Grenadier Division, source: Flickr.com, with permission of the publishing user, edited

The self-propelled gun made an immediately unfavourable impression — a kind of ungainly patchwork creation. Hardly surprising, given that its foundation was a tank whose development had begun twenty years earlier (yes, 1921) and which was hopelessly obsolete. The long tracks running around the entire side of the hull, the complex running gear made up of a large number of small wheels, riveted construction instead of welding — it is genuinely difficult to make something good from such raw material. On the other hand, the entire self-propelled howitzer project was from the outset conceived as a relatively cheap, single-purpose solution (to escort the flame-thrower tanks on the same chassis) with no great ambitions. The end result therefore most likely matched the intention and the resources invested.

Organisation and Deployment

All 16 of the 10.5 cm leFH 18/3 (Sf.) auf Geschützwagen B2 vehicles produced were assigned to the artillery regiment of the 26th Panzer Division, which was stationed in France. The self-propelled guns saw relatively quiet service there, since this was early 1942 and the fighting was happening somewhere far to the east. Nevertheless, reports from the 26th Panzer Division mention frequent breakdowns and unreliability of these vehicles. Under non-combat conditions the problems could apparently be dealt with without major difficulty, as the division still had 15 vehicles of this type in its inventory on 31 May 1943, of which 14 were operational and one was under repair. By that time, however, the division had begun receiving new Wespe self-propelled guns, and the old 10.5 cm leFH 18/3 (Sf.) auf Geschützwagen B2 vehicles were to be handed over to the 90th Panzer-Grenadier Division, newly formed in July 1943 in Sardinia. Whether this transfer actually took place is not known with certainty, but there are photographs showing German soldiers demonstrating a vehicle of this type to their Italian allies, which could suggest the images were indeed taken in Sardinia.

Finally, it is worth noting that individual self-propelled guns were rather unusually identified by large letters from A to P painted on the sides of their fighting compartments.

ARTICLE
CONTENTS:

FRENCH WAR BOOTY

GERMAN CONVERSIONS

DESIGN DESCRIPTION

ORGANISATION AND DEPLOYMENT