Career
The Knight"s Cross of the Iron Cross was awarded to recognise extreme battlefield bravery or successful military leadership. On 26 June 1941, Keller was killed after he collided in mid-air with a Fi 156. During his career he was credited with 23 victories, 16 on the Western Front, four on the Eastern Front and three during the Spanish Civil War.
He was posthumously awarded the Knight"s Cross on 9 July 1941.
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