Though there had been no significant tank-versus-tank engagements during the Polish campaign, German planners were aware that against the French and British, they would face superior numbers, better armed and armored vehicles, and not least stronger antitank defenses. As the Wehrmacht began the process of deploying westward, the armored force underwent a major restructuring.
First to go were the light divisions. Field experience confirmed the prewar decision to concert them to panzer formations. While they had generally performed well enough on the move, lack of tanks proved a major handicap whenever it came to fighting. Adding a company of mediums was unlikely to remedy the problem. Instead they were renumbered as the 6th through the 9th Panzer Divisions and given a two-battalion tank regiment (a single battalion in the case of the 9th). Increased production of Panzer IIIs and IVs resulted in new tables of organization as well. In February 1940 every tank battalion was authorized two light companies, each with two platoons of Panzer IIs and two of Panzer IIIs, and a third “medium” company with a platoon of five Panzer IIs and two platoons totaling seven Panzer IVs; more larger tanks would be issued as they arrived.
That was the theory. In fact, the new tanks trickled in during the winter and spring of 1940. The gap was filled in part by delivery of the 38(t). Around a hundred each went to the 7th and 8th Panzer Divisions (the 6th had the older 35(t)); the other seven divisions had German vehicles, including a significant number of Panzer Is—around a hundred in the 3rd, 4th, and 5th. The next campaign would still be a light tank operation, with all the accompanying implications for better and worse.
In one respect the tanks would be even lighter than desired. The Panzer IIIs coming into the battalions were models E and F, with 30mm of frontal armor and the highest standard of reliability in the armored force. The gun, however, was the original 37mm. The Weapons Office and the armored force alike had originally wanted a heavier piece. A 50mm/42-caliber gun was available; the tank’s turret and turret ring had even been designed to mount larger weapons, but retooling would reduce production at a time when every tank counted. Only a few of the up-gunned versions would see action in the western campaign.
Experience in Poland indicated that the motorized divisions were too large to be controlled in mobile operations. Each shed a regiment, usually transferred to a panzer division organically short of infantry. The Cavalry Rifle Regiments and the reconnaissance formations of the former light divisions were reorganized to panzer division standards with some anomalies—including the troopers’ pride that kept them wearing cavalry yellow branch insignia instead of donning infantry white. Armored half-tracks remained part of Heine’s “airy empire of dreams” for all except a few companies in the 1st, 2nd, and 3rd Panzer Divisions—the privilege of seniority.
As long as the infantry rode trucks, battle group system or no, they would be thrown sufficiently on their own resources to make organic support weapons vital: medium mortars, 37mm light infantry guns, 37mm antitank guns. In contrast to the foot-marching infantry, these were usually assigned to battalions. That in turn gave regimental headquarters more time to train in handling combined-arms formations, as opposed to using attached tanks as generic close support. The rifle companies and battalions, for their parts, intensified assault training, working independently and with the divisional pioneers to break the way for the tanks and then keep pace with them as they advanced.
A few other mobile formations existed as well. Two battalions of Panzer IIs converted to flamethrowers were authorized in the spring of 1940. The 40th Panzer Battalion for Special Purposes was organized with three companies of Panzer Is and IIs and a few experimental types for the invasion of Denmark and Norway. A two-regiment motorized brigade participated in the Danish phase of the operation. Far more significant was the appearance of the Grossdeutschland Regiment. Its ancestor was the Berlin Security Battalion, originally formed under Weimar to safeguard the government and showcase the Reichswehr. In 1937 it was expanded to regimental strength. Recruited, like the former Prussian Guard, throughout the Reich, it was considered a corps d’elite and in 1940 it included four battalions. Three were standard motorized infantry. The 4th, prefiguring later developments in the motorized infantry, was a support battalion with an infantry gun company, an antitank company, and something entirely new: an assault gun battery of six self-propelled 75mm mounts.
The assault gun was a product of exigency: a substitute for the heavy tanks projected in the 1930s for direct infantry support; and a consequence of branch rivalry in the German army. Had rearmament progressed in the systematic fashion envisaged by the General Staff and the High Command, or had Hitler adjusted his diplomatic offensive more closely to Germany’s military capacity, assault guns might well never have existed. Their institutional patron was the artillery. Responding to the nascent armored force’s call for tanks to be concentrated under its command, Germany’s gunners argued that infantry support would inevitably suffer. Experience indicated that weapons in a different branch- of-service chimney were all too likely to be totally elsewhere when needed.
During World War I, the artillery had responded by forming specialized “infantry gun batteries,” armed with modified field guns—an approach unique to the German army. There had never been enough of them, and in the 1920s the Reichswehr had developed two purpose-designed infantry guns, one 75mm and the other 150mm—the same caliber as the standard medium howitzer. Introduced in regimental gun companies, they were useful but disproportionately vulnerable, especially at close range. Their crews, moreover, wore infantry-branch white, and the cannon cockers saw themselves being relegated to third place in the combat arms pecking order.
In 1935, Erich von Manstein, newly appointed head of the General Staff ’s Operations Section, prepared a memo consolidating previous discussions and recommending the development of a self-propelled “assault gun” to work directly with the infantry, with each division having its own battalion. What the gunners described, and what the Weapons Office turned into a development contract in 1936, was to a degree a throwback to the original Allied tanks of World War I: a vehicle with a low silhouette for concealment “not to exceed the height of a standing man,” all- round armor protection, and a 75mm gun with both high-explosive and armor-piercing capacity. Putting those requirements together made a turret impossible; the gun would instead be mounted in a fixed superstructure with a limited traverse of 30 degrees. Initially, as in the later US tank destroyers, the top was open to facilitate the observation considered necessary for tactical effectiveness at infantry ranges. Before going into production, however, the vehicle was given a roof and a panoramic sight enabling it to employ indirect fire. After all, assault guns were artillery weapons.
Guderian, the armored force’s designated pit bull, argued that the concept was a mistake. Turreted tanks could do anything assault guns could do; the reverse was not the case. A subtext amounting to a main text was that the projected assault gun would use the chassis of the Mark III tank and the gun intended for the Panzer IV. Guderian and his tanker colleagues were not placated by projections indicating that rising production would avert serious competition for chassis. A disproportionate number of officers in senior army appointments had begun their careers in the artillery—Fritsch, Beck, and Halder, among others. It has been suggested that a “gunner mafia” thwarted Guderian out of branch rivalry. More to the point was the fact that the light tanks that were expected to become surplus as the IIIs and IVs entered service were too small and fragile to carry a three-inch gun even in a hull mounting, while the artillerymen wanted every active infantry division to have its assault gun battalion by the fall of 1939.
In practice, assault guns never became a high-priority item. The first soft-steel experimental models were not completed until 1938. The first production run was only 30, and those were not delivered until May 1940. Only a half dozen six-gun batteries saw action in France. Later orders placed in early 1940 were for only 120 vehicles—hardly evidence of either branch or institutional commitment to the concept. Not until the Sturmgeschütz III proved its worth beyond question did the contracts expand and the assault gun begin to take its place beside the panzers in Wehrmacht history and military lore.