Hoepner also took part in Operation Barbarossa where he commanded the 4th Panzer Army. His troops attacked Leningrad before being transferred to the AG Centre and fought under Gunther von Kluge on the advance to Moscow.
By 5th December, 1941, Hoepner was only 20 miles north of the capital. However, following a counter-attack by the Red Army, Hoepner decided to withdraw his troops to save them from annihilation. Adolf Hitler was furious when he heard the news and Hoepner was cashiered. After protests from senior figures in the German Army, Hoepner was allowed to retire and was able to retain his pension rights.
In 1944 Hoepner joined the plot to overthrow Adolf Hitler . After the failed July Plot Hoepner was arrested and after being found guilty of treason was hanged at Ploetzwnsee Prison on 8th August, 1944.