The House of Mansfeld was a princely German house, which took its name from the town of Mansfeld in the present-day state of Saxony-Anhalt. Mansfelds were archbishops, generals, supporters as well as opponents of Martin Luther, and Habsburg administrators.
Upon the revolt instigated by the Wettin margrave Dedi I in 1069, Emperor Henry IV appointed the loyal House of Mansfeld counts (Grafen) in the Saxon Hassegau at Eisleben. The family progenitor, Count Hoyer I of Mansfeld, also known as Hoyer the Great, was a field marshal in the service of Emperor Henry V. He was killed at the Battle of Welfesholz on 11 February 1115, fighting the rebellious Saxon forces under Count Lothair of Supplinburg.
The Mansfelds held extended fiefs both in the Archbishopric of Magdeburg and the Bishopric of Halberstadt. The male line became extinct for the first time upon the death of Count Burchard of Mansfeld in 1229; his daughter Sophia married a scion of the Lords of Querfurt, who assumed the comital title. In the 15th century, the primary house divided into cadet branches: Hinterort, Mittelort, and Vorderort, while their County of Mansfeld in 1512 joined the Upper Saxon Circle as an immediate Imperial estate.
Things worsened with the Protestant Reformation: While Count Hoyer VI of Mansfeld-Vorderort (1477-1540) remained a loyal supporter of the Catholic faith, the Mittelort and Hinterort branches sided with Martin Luther. When the county was devastated during the German Peasants' War, Count Albert VII of Mansfeld-Hinterort (1480-1560) not only fought with the Imperial troops in the 1525 Battle of Frankenhausen, but also signed the Protestant Augsburg Confession in 1530 and joined the Schmalkaldic League, wherefore he was banned by Emperor Charles V after the 1547 Battle of Mühlberg.