12 January 1944, the latest Red Army assault managed to lift the 900-day Siege of Leningrad, during which over 1,000,000 people had died and on 20 January German troops started to retreat. The re-conquering of the Baltic area was undertaken as a direct follow through of the assault that started in Leningrad, entering Estonia in early February, along with much of Ukraine and Belarus. Nazi Germany began to suffer regular defeats on the eastern front and was pushed back to the west. The 2nd Latvian SS Brigade which was now upgraded to the 19th Waffen Grenadier Division of the SS (2nd Latvian), was amongst those fighting before the spring thaw slowed the attacks. On 22 June, the third anniversary of the German invasion was chosen as the start date for Operation Bagration. The massive Soviet attack was catastrophic for the German armies who fell back before the onslaught. It was mid-July 1944 before the Soviet Army once again crossed Latvia's pre-war eastern border, the Soviet armies continued westward leaving sufficient troops to block in the remaining German forces until they attacked on 11 September as a diversion for an attack in Estonia. On 9 October Riga was in artillery range of the Red Army. German troops, including the 19th Waffen Grenadier Division of the SS (2nd Latvian) under the code name Donner (Thunder), withdrew from Riga, destroying bridges as they went. Battles were quite bloody but by 13 October 1944 the Soviets had re-captured Riga. By mid October, the German Army, which partly included the "Latvian Legion", was besieged in Kurzeme, in the "Courland Pocket". Some 200,000 German troops held out in Courland. They were trapped between the Baltic Sea and the Soviet lines while the Soviet Army concentrated on attacks in East Prussia, Silesia, Pomerania, and ultimately Berlin. Colonel-General Heinz Guderian, the Chief of the German General Staff, insisted that the troops in Courland be evacuated by sea and used for the defense of the Reich. However, Hitler refused and ordered the German forces in Courland to hold out. He believed them necessary to protect German submarine bases along the Baltic coast. On January 15, 1945, Army Group Courland () was formed under Colonel-General Dr. Lothar Rendulic. Until the end of the war, Army Group Courland (including divisions such as the Latvian Freiwiliger SS Legion) successfully defended the area in which they were besieged. It held out until May