Harald Gille, king of Norway, was murdered by Sigurd Slembe in 1136, leaving behind a contested succession. Inge, the only legitimate son, born to Ingirid Ragnvaldsdottir, was named king while still a child. His half-brothers Magnus and Sigurd received the same title, creating a tripartite rule over Norway that functioned only because none of the brothers was strong enough to eliminate the others. Inge was physically disabled from birth, described in the sagas as hunchbacked and with one leg shorter than the other, earning him the byname Krokrygg, meaning crookback. Despite his condition, he proved politically capable. He outlasted both brothers: Magnus fell in 1145, and Sigurd died in 1155. For a brief period, Inge ruled Norway alone.

Haakon, an illegitimate son of Harald Gille, had been raised as a potential claimant but lacked the legitimacy Inge held. By 1161, Haakon had gathered enough support to challenge his half-brother directly. On the night of February 3, the two forces met outside Oslo. According to the Heimskringla, the great saga compilation of Snorri Sturluson, Inge commanded approximately 4,800 men. The details of the battle are sparse in the surviving sources, but the outcome was decisive: Inge I was killed. The king who had survived childhood disability, outlived two rival brothers, and held Norway together through decades of civil strife fell in a night engagement on frozen ground outside his own capital.

Inge's death did not end Norway's civil wars. Haakon II assumed power but ruled for only two years before he too was killed, in 1162, at the Battle of Sekken. The cycle of succession violence, rival claimants, and shifting alliances that had defined Norwegian politics since the early 12th century continued for decades. The battle outside Oslo was one episode in a longer pattern: a kingdom rich in coastline and resources but lacking the institutional structures to manage peaceful succession. The saga writers recorded these events with a mix of admiration and fatalism, treating the violence as both tragic and inevitable. Oslo itself, not yet the fortified capital it would become when Akershus Fortress was built a century later, was simply the stage on which one more king fell.