The failure of Emperor Charles III to halt the Viking raids on the East Frankish kingdom results in his overthrow by the East Frankish magnates.

Arnulf takes the leading role in the deposition of his uncle.

With the support of the nobles, Arnulf holds a Diet at Tribur and deposes Charles in November 887, under threat of military action.

Charles peacefully goes into his involuntary retirement, but not without first chastising his nephew for his treachery and asking only for a few royal villas in Swabia, which Arnulf mercifully grants him, on which to live out his final months.

Arnulf, having distinguished himself in the war against the Slavs is elected by the nobles of the realm (only the eastern realm, though Charles had ruled the whole of the Frankish lands) and assumes his title of King of East Francia.