Development of the Panzerjäger I, the German tank destroyer, started in 1939 based on the Panzerkampfwagen I Ausf. B. Initially, the 37-mm Pak 36 gun was mounted on the chassis of the Panzerkampfwagen I Ausf. B. However, during the invasion of Poland, it was revealed that the gun was not effective against new vehicles. After Germany captured Czechoslovakia in 1940, the 47-mm Pak 36(t) L/43.4 (Škoda 47-mm A-5 KP ÚV vz. 38 Model A5) gun was mounted on the tank destroyer. A total of 202 vehicles were manufactured and saw action until 1943.