On 1 August 1944, the underground Polish Home Army, loyal to the Polish government-in-exile in London, began the 63-day long Warsaw Uprising, an attempt to free the city from the occupying German forces before the arrival of the Red Army. On 15–23 September, when the uprising was in its later phase, with his First Polish Army on the east bank of the Vistula River and the Praga district of Warsaw already secured, Berling led a rescue effort that involved crossing the Vistula and establishing a bridgehead on the west bank. The failed operation, possibly not fully consulted with Berling's Soviet military superiors, resulted in heavy Polish Army casualties and may have caused Berling's dismissal from his post soon thereafter. He was transferred to the War Academy in Moscow, where he remained until his return to Poland in 1947. In Poland, Berling organized and directed the Academy of General Staff ("Akademia Sztabu Generalnego"). He retired from the military in 1953.