After succeeding his father, he improved the defense and settlement of Brandenburg and waged campaigns against the Slavs and Canute VI of Denmark. In the winter of 1198–99 he devastated Danish-occupied Pomerania and consolidated his territorial gains in the subsequent year with a campaign that pressed to Rügen and threatened Hamburg. In 1200 and 1203, he supported the Hohenstaufen king Philip of Swabia against the WelfenHoly Roman Emperor, Otto IV.
Succession
After his death, his half-brother Albert II inherited the margraviate.
Helmut, Assing (1997). Brandenburg, Anhalt und Thüringen im Mittelalter. Askanier und Ludowinger beim Aufbau fürstlicher Territorialherrschaften (in German). Cologne: Böhlau Verlag. ISBN3-412-02497-X.
Helmut, Assing (2002). Die frühen Askanier und ihre Frauen (in German). Bernburg.
Lutz, Partenheimer (2001). Albrecht der Bär — Gründer der Mark Brandenburg und des Fürstentums Anhalt (in German). Cologne: Böhlau Verlag. ISBN3-412-16302-3.
Lyon, Jonathan R. (2013). Princely Brothers and Sisters: The Sibling Bond in German Politics, 1100–1250. Cornell University Press.