Events Albert I of Brandenburg begins his ruthless program to pacify the Slavic region. June 11 - Albert I of Brandenburg, also called, The Bear (Ger: Albrecht der Bär), becomes the founder of the Margraviate of Brandenburg, Germany and the first Margrave. August 21 - Sancho III and Ferdinand II, the sons of King Alfonso VII of Castile, divide his kingdom between them upon his death. October 23 — Battle of Grathe Heath: A civil war in Denmark ends with the death of King Sweyn… (More on 1157)