His mother was the last of the Farnese, rulers the Duchy of Parma. The Duchy had been ruled between 1731 and 1736 by his elder brother Charles I, but exchanged with Austria for The Two Sicilies after the War of Polish Succession. Twelve years later, in the Treaty of Aix-la-Chapelle (1748), Austria lost Parma, and Philip became the new Duke, founding the Bourbons of Parma.