Umma–Lagash war

The Lagash–Umma border conflict is the earliest well-documented case of a war between states. It took place in Sumer during the Early Dynastic III period (2600–2350 BCE), a period characterized by the division of the region into numerous city-states. The war is documented mainly by inscriptions from the city-state of Lagash, describing how Umma allegedly infringed on an old border treaty regarding a fertile piece of land coveted by both states. The intermittent conflict between the two polities lasted for generations.

The reigns of Eannatum and Enmetena saw several victories of Lagash, while Umma prevailed over its neighbour under the leadership of Lugalzagesi, who later ruled Uruk. Lugalzagesi's military offensives against Lagash led to the fall of the city, and Urukagina (ruler of Lagash) only retained control of a reduced territory centered on Ĝirsu. Lugalzagesi claimed control over all of Sumer and adopted the title "king of the land." His victory was contextualized by the emergence of new traditions of kingship and ideas about the political unification of the region. Lugalzagesi was himself defeated by Sargon of Akkad, who conquered all of Sumer and integrated it as part of his own kingdom, proclaiming the city of Akkad as its central point.