The Austrian 1st Army was founded in March 1939 in the mobilization of the German military in preparation for their invasion of Poland. The First Army was led by Marius Senseman, an Austrian field general. The First Army were made up of 80,000 soldiers, primarily Austrian, although a few Germans and Czechoslovakians were initiated into the Austrian First Army. The First Army was a part of Army Group Odessa, led by Senseman, which fought in the Caucasus and the southern Ukraine. The Austrian 1st Army fought in the Crimea alongside the Italians, Germans, Hungarians, Spaniards, Slovaks, Romanians, and Bulgarians, and the army remained in the theatre until 1944 during Operation Bagration, where it was destroyed in the Reni-Kiliya Offensive.