The Battle of the Seelow Heights () was part of the Berlin Strategic Offensive Operation (16 April–2 May 1945). A pitched battle, it was one of the last assaults on large entrenched defensive positions of the Second World War. It was fought over three days, from 16–19 April 1945. Close to 1,000,000 Soviet soldiers of the 1st Belorussian Front (including 78,556 soldiers of the Communist Polish 1st Army), commanded by Marshal Georgy Zhukov, attacked the position known as the "Gates of Berlin". They were opposed by about 110,000 soldiers of the German 9th Army, commanded by General Theodor Busse, as part of the Army Group Vistula. This battle is often incorporated into the Battle of the Oder–Neisse. The Seelow Heights was where some of the most bitter fighting in the overall battle took place, but it was only one of several crossing points along the Oder and Neisse rivers where the Soviets attacked. The Battle of the Oder–Neisse was itself only the opening phase of the Battle of Berlin. The result was the encirclement of the German 9th Army and the Battle of Halbe. Buildup On 9 April 1945, Königsberg in East Prussia fell to the Soviet Army. This freed the 2nd Belorussian Front under Marshal Konstantin Rokossovsky to move to the east bank of the Oder. During the first two weeks of April, the Soviets performed their fastest front redeployment of the war. The 2nd Belorussian Front relieved the 1st Belorussian Front along the lower Oder between Schwedt and the Baltic Sea. This allowed the 1st Belorussian Front to concentrate in the southern half of its former front, opposite the Seelow Heights. To the south, the 1st Ukrainian Front under Marshal Ivan Konev shifted its main force from Upper Silesia north-west to the Neisse River. The three Soviet fronts together had 2,500,000 men, 6,250 tanks, 7,500 aircraft, 41,600 artillery pieces and mortars, 3,255 truck-mounted Katyusha rocket launchers and 95,383 motor vehicles. The 1st Belorussian Front had nine regular and two tank armies consisting of 77 rifle divisions, two cavalry, five tank and two mechanized corps, eight artillery and one guards mortars divisions and a mixture of other artillery and rocket launcher brigades. The front had 3,059 tanks and self-propelled guns and 18,934 artillery pieces and mortars. Eight of the 11 armies were posted along the Oder. In the north, the 61st Army and the 1st Polish Army held the