- Period:
 - Second World War (1939-1945)
 - Rank:
  - Oberleutnant der Reserve (Lieutenant)
 - Unit:
  - Chef  7. / Panzer-Regiment "Großdeutschland" 
 - Awarded on:
  - September 10th, 1943
 
During the German Operation Citadel Oberleutnant Lex commanded a Kompanie of Panzer IV tanks. On the 15.07.1943 he and his Panzers were deployed as security to the west. Near Nowenskoje Lex recognized a Soviet tank assembly area, and without hesitating decided to catch the enemy armour there in a surprise attack. The Soviets were unable to offer effective resistance and soon lost 16 tanks while failing to knock out a single German tank.
By his independent action Lex had thus eliminated a potential flank threat to the German forces in this area at minimal cost. He would be decorated with the Knight’s Cross in recognition.