After the Polish surrender, he was made Commander-in-Chief of the 2nd Army, a part of Rundstedt's Army Group A in the West. After the Battle of France, he was awarded the Knight's Cross of the Iron Cross and promoted to colonel-general. Leading his army, Weichs later took part in the Balkans Campaign, and in preparation for Operation Barbarossa, the German invasion of the Soviet Union, he was assigned to lead the 2nd Army as a part of Fedor von Bock’s Army Group Centre. He led the 2nd Army in 1941 through the Battle of Kiev, the Battle of Smolensk, and then on to Vyazma and Bryansk.