During World War I Halder was a member of the staff of the Crown Prince of Bavaria where he left his mark as an outstanding officer. In 1938 BECK resigned as Chief of General Staff and Halder was appointed to replace him. Halder was not an admirer of HITLER and lent his support to various conspiracies to have him arrested, none of which materialized. Halder planned and led the invasions of Poland and of France. He warned Hitler against pursuing his Western offensive in 1939 but Hitler went ahead in May 1940, in spite of Halder’s advice. Halder helped to plan the invasion of England and the attack on Russia in 1941. In December 1941 BRAUCHITSCH resigned and Hitler took over as Commander in Chief of the German Armed Forces. Halder continued as Chief of General Staff but was finally replaced by ZEITZLER in September 1942. He was arrested after the 1944 Bomb Plot against Hitler and was interned at Dachau. He was freed in 1945 and gave important evidence at Nuremberg.