Adolf Hitler (third from right, Führer und oberster Befehlshaber der Wehrmacht) inspecting one of the first twenty Jagdpanzer 38 (Sd.Kfz.138/2) "Hetzer" (Baiter or Troublemaker) during official presentation for the 55th Führer's birthday at Arys (Orzysz) in East Prussia, 20 April 1944. After the demonstration they were sent directly back to the factory since they were not yet completely serviceable. The name "Hetzer" was at the time not commonly used for this vehicle. It was the designation for a related prototype, the E-10. The Škoda factory for a very short period confused the two names in its documentation and the very first unit equipped with the vehicle thus for a few weeks applied the incorrect name until matters were clarified. However, there exists a briefing paper from Heinz Guderian to Hitler claiming that an unofficial name, Hetzer, had spontaneously been coined by the troops. Post-war historians basing themselves on this statement made the name popular in their works, though the vehicle was never named as such in official documents!