The First Battle of Petrozsény was a military engagement fought between Romanian forces on one side and German forces on the other side. It was part of the 1916 Battle of Transylvania, itself part of the Romanian Campaign of World War I. This was a German attack which drove off the Romanian forces from the Transylvanian coal mining center of Petrozsény. Although a Romanian counterattack a few days later undid most of their gains, the main strategic objective of the Central Powers had been nevertheless achieved.

The First Army was a field army of the Romanian Land Forces, active from 1916 to 2000. The successor of the First Army was the 1st Infantry Division.