In June 1943, the 3rd Sandzak Brigade left the division, and in November 1943, the 13th Proletarian Brigade joined the Division. From September 1, 1943, the First Proletarian Division was part of the 1st Proletarian Corps. The division also included the Seventh Krajina Brigade from mid-July to mid-August 1943, the Eighth Montenegrin Brigade from November 6, 1944 to February 7, 1945, the "Italy" Brigade (composed of Italian volunteers) from October 29, 1944, and the Artillery Brigade of November 21, 1944. Since November 1943, the Thirteenth Proletarian Strike Brigade "Rade Končar" has been included in its composition, with which it went through fierce fighting during the winter operations of 1944, known as Operation Reselšprung, the Durmitor Operation, the offensive in western Serbia in September 1944, the Belgrade offensive and the Syrmian Front.