From 1938 Purkayev served as the Chief of Staff of the Belorussian Military District, as the Soviet military attaché in Berlin at the start of the Second World War in 1939, and participated in planning of the Soviet invasion of Poland. From July 1940, Purkayev served as the Chief of Staff of the Kiev Special Military District, and from the start of the Soviet-German War serving as the Chief of Staff of the Southwestern Front (June–July 1941), and later the 60th Army and 3rd Shock Army. In 1942–43 he served as commander of the Kalinin Front and from April 1943, the Far Eastern Front (from 1945 2nd Far Eastern Front). From September 1945 to January 1947 Purkayev served as the commanding officer of the Far Eastern Military District during which time he was nominated to the Supreme Soviet of USSR (1946–1950).