Context : Karl Borris (3 January 1916 -- 18 August 1981) was a German Luftwaffe ace and recipient of the Knight's Cross of the Iron Cross (German: Ritterkreuz des Eisernen Kreuzes) during World War II. The Knight's Cross of the Iron Cross was awarded to recognise extreme battlefield bravery or successful military leadership. 
Question : What was the award received by Karl Borris?
Knight's Cross of the Iron Cross