army was a unit of the German Army Group A, under command of Gerd von Rundstedt. It was this Army Group that successfully forced the Ardennes and then made the imperative break-through on 15 May 1940, which spread panic in the French forces and cut the British expeditionary forces off from their supply lines. After this successful campaign List was among the twelve generals that Hitler promoted to Field Marshal during the 1940 Field Marshal Ceremony. In early 1941, German troops were being steadily massed on the Eastern Front of the Third Reich, in preparation for Operation Barbarossa, the German invasion of the Soviet Union. OKW believed that before Barbarossa could be launched it would be necessary to eliminate the possibility of interference from Greece by militarily subduing this country, in an operation codenamed Operation Marita. List was delegated to negotiate with the Bulgarian General Staff, and a secret agreement was signed allowing the free passage of German troops through Bulgarian territory. On the night of 28/29 February 1941, German troops—including List, who now commanded the 12th Army—took up positions in Bulgaria, which the next day joined the Tripartite Pact. Invasion of Greece and Yugoslavia On 6 April 1941 the Wehrmacht launched invasions both of Greece and of Yugoslavia. List's 12th Army, consisting of four armored divisions and 11 motorized infantry divisions, totally outmatched the defending forces. German forces occupied Belgrade on 13 April and Athens on 27 April. The mainland Balkans campaign ended with the evacuation of British forces on 28 April. In the Balkans List became implicated in the mass murder of hundreds of thousands of civilians by having ordered hostage-taking and reprisal killings. Summer campaign of 1942 and dismissal In early July 1942, List took command of Army Group A, newly formed from the split of Army Group South during the Germans’ summer offensive named Case Blue. His orders were to take Rostov and then advance into the Caucasus to take oil rich areas of Maikop and Grozny. German forces made good progress for two months, taking Maikop and almost to Grozny, about from Rostov. However, by the end of August their advance had ground to a halt, chiefly due to considerably stiffened Soviet resistance, and also due to critical shortages of fuel and ammunition as the army group outran its supply lines. Matters were made worse for the Germans by the removal in mid-August of most