In June 1941, Hitler launched Operation Barbarossa, the invasion of the Soviet Union, and all the Waffen-SS formations participated. SS Division Nord in northern Finland fought alongside the Finnish Army in the battle of Salla, where they suffered severe losses in the first two days of the invasion due to the thick forests and heavy smoke from forest fires. However, the rest of the operation’s forces fared much better. The SS Totenkopf and Polizei divisions advanced through the Baltic States and on to Leningrad, while the SS Division Das Reich headed towards Moscow. The war in the Soviet Union proceeded well at first, but the cost to the Waffen-SS was extreme. By late October, the Leibstandarte was at half strength due to unexpected enemy action and dysentery that swept through the ranks. Das Reich lost 60% of its strength and was still to take part in the Battle of Moscow. The unit was decimated in the following Soviet offensive. The Der Führer Regiment was reduced to 35 men out of the 2,000 that had started the campaign in June. Altogether, the Waffen-SS had suffered 43,000 casualties in the fight for the Soviet Union.