The Panzerkampfwagen 38(t), which originally was known as the ČKD LT vz. 38 when created in Czechoslovakia, was a design from the 1930s that was a mainstay in early WWII. It was adopted by the Germans after they annexed Czechoslovakia and saw service in Poland, France, and on the Eastern Front. The armament proved to be outmatched early on and production ended around 1942. Around 1400 were made, and the chassis continued to be a foundation for the Marder III and modified for the Jagdpanzer 38.
The Ausf. E & F were built between late 1940 and late 1941 and saw improvements to armor thickness (to 50mm) with an extra 25mm of bolted-on applique armor to the front glacis and improvements to the mantlet as well. Other improvements to storage and hardpoints were added to the mudguards.