chance of German victory or even stalemate in the east. The Soviet victory at Kursk marked the end of German superiority, giving the Soviet Union the initiative on the Eastern Front. The Germans tried to stabilise their eastern front along the hastily fortified Panther–Wotan line, but the Soviets broke through it at Smolensk and by the Lower Dnieper Offensive. On 3 September 1943, the Western Allies invaded the Italian mainland, following Italy's armistice with the Allies and the ensuing German occupation of Italy. Germany, with the help of fascists, responded to the Armistice by disarming Italian forces that were in many places without superior orders, seizing military control of Italian areas, and creating a series of defensive lines. German special forces then rescued Mussolini, who then soon established a new client state in German-occupied Italy named the Italian Social Republic, causing an Italian civil war. The Western Allies fought through several lines until reaching the main German defensive line in mid-November. German operations in the Atlantic also suffered. By May 1943, as Allied counter-measures became increasingly effective, the resulting sizeable German submarine losses forced a temporary halt of the German Atlantic naval campaign. In November 1943, Franklin D. Roosevelt and Winston Churchill met with Chiang Kai-shek in Cairo and then with Joseph Stalin in Tehran. The former conference determined the post-war return of Japanese territory and the military planning for the Burma campaign, while the latter included agreement that the Western Allies would invade Europe in 1944 and that the Soviet Union would declare war on Japan within three months of Germany's defeat. From November 1943, during the seven-week Battle of Changde, the Chinese forced Japan to fight a costly war of attrition, while awaiting Allied relief. In January 1944, the Allies launched a series of attacks in Italy against the line at Monte Cassino and tried to outflank it with landings at Anzio. On 27 January 1944, Soviet troops launched a major offensive that expelled German forces from the Leningrad region, thereby ending the most lethal siege in history. The following Soviet offensive was halted on the pre-war Estonian border by the German Army Group North aided by Estonians hoping to re-establish national independence. This delay slowed subsequent Soviet operations in the Baltic Sea region. By late May 1944, the Soviets had liberated Crimea, largely expelled Axis forces from Ukraine, and made incursions into Romania, which were repulsed by