Battle of Lenzen: Slavic forces (the Redarii and the Obotrites) are defeated by a Saxon army near the fortified stronghold of Lenzen in Brandenburg.

The Battle of Lenzen was a land battle between a Saxon army of the Kingdom of Germany and the armies of the Slavic Redarii and Linonen peoples, that took place on 4 September 929 near the fortified Linonen stronghold of Lenzen in Brandenburg, Germany. The Saxon army, commanded by Saxon magnate Bernhard, destroyed a Slavic Redarii army. It marked the failure of Slavic attempts to resist German king Henry the Fowler's expansionism to the Elbe.

The Slavs or Slavic people are groups of people who speak Slavic languages. Slavs are geographically distributed throughout the northern parts of Eurasia; they predominantly inhabit Central Europe, Eastern Europe, Southeastern Europe, and Northern Asia, though there is a large Slavic minority scattered across the Baltic states and Central Asia, and a substantial Slavic diaspora in the Americas, Western Europe, and Northern Europe.

The Veleti, also known as Veletians, Wilzi, Wielzians, and Wiltzes, were a group of medieval Lechitic tribes within the territory of Western Pomerania, related to Polabian Slavs. They had formed together the Confederation of the Veleti, also known as the Union of the Veleti, a loose monarchic confederation of the tribes. Said state existed between the 6th and 10th centuries, after which, it was succeeded by the Lutician Federation.

The Obotrites or Obodrites, also spelled Abodrites, were a confederation of medieval West Slavic tribes within the territory of modern Mecklenburg and Holstein in northern Germany. For decades, they were allies of Charlemagne in his wars against the Germanic Saxons and the Slavic Veleti. The Obotrites under Prince Thrasco defeated the Saxons in the Battle of Bornhöved (798). The still-Pagan Saxons were dispersed by the emperor, and the part of their former land in Holstein north of Elbe was awarded to the Obotrites in 804, as a reward for their victory. This however was soon reverted through an invasion of the Danes. The Obotrite regnal style was abolished in 1167, when Pribislav was restored to power by Duke Henry the Lion, as Prince of Mecklenburg, thereby founding the Germanized House of Mecklenburg.