Blomberg remained in the army and unlike a large number of senior officers was not purged by Adolf Hitler and in March 1939 led German troops into Czechoslovakia. Promoted to the rank of Generaloberst and was involved in the invasions of Poland and France. Bock was shocked by the way the Schutz Staffeinel (SS) treated Jews in Poland but decided against an official protest. In 1940 he was one of twelve new field marshals created by Hitler.
During Operation Barbarossa Bock was given the task of capturing Moscow. In July 1941 his AG centre troops captured Minsk and three weeks later he had reached Smolensk. Bock was now only 225 miles from Moscow but Adolf Hitler took the decision to divert some of his army to Leningrad and Kiev. It was not until October that Bock was able to resume his advance on Moscow.
Bad weather forced Bock to halt his advance on Moscow in December, 1941. Hitler replaced Bock by Gunther von Kluge but after only a month's rest, he was sent once again to the Soviet Union to take control of AG South after the death of Walther von Reichenau.
Hitler told Bock to destroy Soviet forces west of the Don and to gain control of the Caucusus oil fields. He initially had success at Voronezh but disappointed with his slow progress, Hitler replaced Bock with Zur Glon Weichs.
In 1944 Bock was approached by his nephew Henning von Tresckow, about the possibility of joining the July Plot against Adolf Hitler. Bock refused but did not pass details onto the Gestapo. Fedor von Bock and his wife and daughter were killed on 4th May 1945 during an Allied air raid on Hamburg.