The Battle on the Raxa river (German: Schlacht an der Raxa) was fought on 16 October 955 over control of the Billung march (in present-day Mecklenburg-Vorpommern, northeast Germany) between the forces of Otto I of Germany allied with the Rani tribe on one side, and the Obotrite federation under Nako and his brother Stoigniew (Stoinef, Stoinneg, Stoinegin, Ztoignav) with their allied and tributary Slav neighbours on the other. The Raxa river is identified with either the Recknitz or the Elde river. The German victory over the Slavs followed up on the August victory at the Lechfeld over the Magyars and marked the high point of Otto's reign.
Background
While King Otto was distracted by his campaigns against the Magyars, his vassals Wichmann the Younger and his brother Egbert the One-Eyed instigated a Slav revolt in the Billung March. The Obotrites invaded Saxony and sacked the Cocarescemians' settlement, killing the men of arms-bearing age and carrying off the women and children into slavery. According to Widukind of Corvey, in the aftermath of Lechfeld, Otto pressed hard into Slav territory, where Wichmann and Egbert had sought refuge.
Otto razed the Slav population centres and soon had encircled them; he offered to spare his enemies if they would surrender. A Slav embassy came to an assembly Otto held in Saxony and offered to pay annual tribute in return for being allowed self-government; "otherwise," they said, they would "fight for their liberty." Reuter argues that this is indicative of a change in German governing practice: a change from overlordship, which the Slavs were willing to accept, to lordship, which the Slavs protested.
Dendrodates reveal that in the context of the Saxon-Obotrite conflict, the Slavs in present-day northeast Germany started to build many forts – only few forts were built before. A second phase of extensive fort construction occurred in the 980s, in the context of the great uprising of 983.
Contemporary accounts
The course of the battle is described in Widukind of Corvey's chronicle Rerum gestarum Saxonicarum lib. III c. LIII-LV and, in less detail, in Thietmar of Merseburg's Chronicon lib. II.12. Short mentions of the battle are recorded in the respective paragraphs about the year 955 in the continuation of the annals of Prüm Abbey and the annals of St. Gallen Abbey.