 Living in exile in 1551, the Habsburgs turned to him to rule Wallachia as a leader devoted to their cause.Backed by Habsburg general Johann Baptist Castaldo, he invaded Wallachia in 1552, and, on November 16, defeated the ruler of Wallachia, Mircea the Shepherd.He won the Battle of Mănești (Prahova) on November 15, 1552 and Mircea the Shepherd fled to Giurgiu.