Background
His mother was Ernst II"s second wife, Dorothea von Solms-Lich.
His mother was Ernst II"s second wife, Dorothea von Solms-Lich.
Born in Heldrungen, Saxony, he was the 11th child (of 16) of Ernst II, von Mansfeld-Vorderort. As a young man, Peter Ernst came to the Spanish Netherlands with Charles V. He participated in the expedition against Tunis in 1535 and became governor of Luxembourg in 1545. He was made a knight in the Order of the Golden Fleece in 1546.
In the Eighty Years" War, he took part in combat under John of Austria, the illegitimate half-brother of King Philip II of Spain and Alexander Farnese, cousin on his mother"s side.
He fought amongst others in the Battle of Gembloux (1578). When Farnese invaded France in 1590, Mansfeld was appointed Governor ad interim of the Spanish Netherlands.
When Farnese died in 1592, Von Mansfeld effectively became governor until Archduke Ernest of Austria took over in 1594.