The German 12th Army was assigned the task of executing Operation Marita, which was the codename for the German invasion of Greece. Under the command of Wilhelm List, it was composed of four army corps, reinforced by the 1st SS Division Leibstandarte Adolf Hitler. Pushing southward from Yugoslavia, in the north, the XL Panzer Group constituted the main spearhead of the German advance into Greece, following a line that ran parallel to the Axios River, capturing Thessaloniki first and then Athen as it went. Meanwhile, the XVIII Mountain Corps and the XXX and L Infantry Corps would attack Greece across the Bulgarian border. Under Alexander Papagos, the Greek 2nd Army was charged with the defense of Greece. This army was reinforced with British units. The German 1st Panzer Group, led by Ewald von Kleist, only took part in the invasion of Yugoslavia and the capturing of Belgrade. After the German victory, southern Greece became the springboard from which the German Fallschirmjäger (paratroopers) would invade the Island of Crete.
Maps of the German attack on Greece in April 1941