- Period:
 - Second World War (1939-1945)
 - Rank:
  - Oberleutnant (1st Lieutenant)
 - Unit:
  - stellvertretender Führer II. / Grenadier-Regiment 105 
 - Awarded on:
  - February 18th, 1945
 
Karl Zimmer was awarded the Knight's Cross for actions at Schmerinka, Soviet Union, for leading his Kompanie in house-to-house fighting that re-took a Russian position.