The Lwów uprising (Polish: powstanie lwowskie, akcja Burza) was an armed insurrection by the Home Army (Polish: Armia Krajowa) underground forces of the Polish resistance movement in World War II against the Nazi German occupation of the city of Lviv in the latter stages of World War II. It began on 23 July 1944 as part of a secret plan to launch the countrywide all-national uprising codenamed Operation Tempest ahead of the Soviet advance on the Eastern Front. The Lwów uprising lasted until 27 July. Shortly afterwards, the Polish troops were disarmed, soldiers either arrested or conscripted into the Polish communist armed forces and officers were arrested by the Soviet NKVD. Some were forced to join the Red Army, others sent to the Gulag camps. The city itself was occupied by the Soviet Union.