The Battle of Idris IV was a major engagement during the First Tevarin War between forces of the United Planets of Earth (UPE) and the Tevarin. It took place on 1 October 2544 SEY on and above Idris IV.

Before the battle, the UPE had been losing ground, resulting in the planet being overtaken by Tevarin forces. The tactics of a young Ivar Messer ensured UPE victory at Idris IV and turned the tide of the war. This battle was key in beginning Messer's rise to power. A monument to the battle has been established on Idris IV.