- Second World War (1939-1945)
- Käpitanleutnant (Lieutenant)
- Kommandant, U 107, Kriegsmarine
- Awarded on:
- June 24th, 1941
Awarded for sinking 18 ships (with 105181 GRT) as commander of U-107. Of these, all but 4 were sunk during a single patrol near the Canary Islands. It was primarily for this outstanding achievement that Hessler received the Knight's Cross.