The First Army became one of the Romanian armies fighting for the Red Army on the Eastern Front. In its campaign from August 1944 to May 1945, the Romanian Army lost some 64,000 men killed. At the Battle of Debrecen in October 1944, where Romanian units played a key part in the overall Soviet offensive, the First Army consisted of the 4th Army Corps with the 2nd Infantry Division and the 4th Infantry Division, and the 7th Army Corps with the 9th Infantry Division and 19th Infantry Division. The 7th Army Corps, with the 2nd and 19th Infantry Divisions and what was reported as the 9th Cavalry Division, then took part in the Siege of Budapest as part of the Red Army's 3rd Ukrainian Front.