As Germany attempted to re-arm in the 1930s in the lead-up to WWII, the military leadership relied heavily on the Pz.Kpfw.I. Some 1,493 examples of all types were built and these light tanks served in early campaigns even though they were supposed to be just training platforms. Mass production of the Ausf.A commenced in 1934, while the improved Ausf.B with a different engine appeared in August 1935. The Ausf.B was lengthened and it had five road wheels per side. The Panzer I was thinly armoured with just 13mm steel at its thickest point. It operated with a crew of two – the commander/gunner and driver. An unusual version of this small tank was the Abwurfvorrichtung, literally a Demolition Charge Layer. These modified tanks were typically found in the panzer-pionier-bataillon of panzer divisions in 1940 in time for the campaign in Western Europe. The conversion comprised a device mounted on the rear deck that could lower a 50kg explosive charge onto or against a field fortification before it was then detonated.