An officer in the Wehrmacht, he died during the Battle of Welle shortly before the end of World War II.

On 11–20 August 1939, he, along with Wolfgang Unzicker (14 years old), Edith Keller (17), Rudolf Kunath (15) and Karl Krbavic (17), played in Fürstenwalde (Jugendschachwoche) near Berlin.

In October 1941, he took fourth place, behind Alexander Alekhine, Schmidt, and Efim Bogoljubow, at Kraków/Warsaw (the second General Government chess tournament championship).

Klaus Junge, whose father had been a member of the Nazi Party since 1932,[5] was an adherent of the National Socialist ideology.

As a lieutenant of the Wehrmacht, he died in combat against Allied troops on 17 April 1945 in the Battle of Welle on the Lüneburg Heath, close to Hamburg, three weeks before World War II ended.