Battle of Lenzen

The Battle of Lenzen (30 August - 4 September, 929) was culmination of a series of military operations initiated by Henry the Fowler to extend Saxon rule into the Slavic realms. Lenzen, situated on the Elbe, had a major fortress, protected by a large contingent of Redarii, that was key to meeting Henry’s objectives. Widukind and Thietmar of Merseburg both wrote of the battle, with Thietmar losing two great-grandfathers, both named Lothar (one the Count of Walbeck, the other the Count of Stade), in the battle.

Background
In 921 the Hungarians (Magyars) invaded Germany and Italy. A sizable force was routed near Bleiburg in the Bavarian March of Carinthia by Eberhard and the Count of Meran. Another group was routed by Liutfried, Count of Alsace. Nevertheless, the Magyars repeatedly raided Germany. Henry, having captured a Hungarian prince, managed to arrange a ten-year-truce in 926, though he was forced to pay tributes. By doing so he and the German dukes gained time to fortify towns and train a new elite cavalry force.

During the truce with the Magyars, Henry subdued the Polabian Slavs, settling on the eastern border of his realm. In the winter of 928, he marched against the Slavic Hevelli tribes and seized their capital, Brandenburg. He then invaded the Glomacze lands on the middle Elbe river, conquering the capital Jahna after a siege, and had a fortress (the later Albrechtsburg) built at Meissen. In 929, with the help of Arnulf of Bavaria, Henry entered Bohemia and forced Duke Wenceslaus I to resume the yearly payment of tribute to the king.

Despite these victories, the Slavic Redarii captured the town of Walsleben, and massacred the inhabitants.

Battle of Lenzen
In response to the capture of Walsleben, Henry assembled a large force of Saxons under the command of Counts Bernard and Thietmar to march against the fortress of Lenzen beyond the Elbe. The siege began on 30 August and, after 5 days, the Slavs deployed an infantry phalanx to attack the Saxon forces. Because the ground was wet, the Saxon cavalry were ineffective. However, after fierce fighting, the Saxons completely routed the enemy on 4 September 929. The Lusatians and the Ukrani on the lower Oder were subdued and made tributaries in 932 and 934, respectively. The survivors were either carried into to captivity or beheaded.

Aftermath
Henry, consolidating his victory at Lenzen, had a fortification built at Havelburg. The Ukrani, however, continued their attacks on the Northern March, until their defeat in 954 by Gero, Margrave of the Saxon Eastern March. In 954, Margrave Gero of the Saxon Eastern March (marca Geronis), aided by Holy Roman Emperor Otto I's son-in-law, Conrad of Lorraine, launched a successful campaign to subdue the Ukrani, who had come in reach of the Holy Roman Empire's Northern March after the Battle of Lenzen.