In 1916, Philipp's oldest brother Friedrich Wilhelm died (in World War I) and Philipp became second in line to succeed his uncle as Head of the Electoral House of Hesse. In October 1918, Philipp's father was elected king of Finland. It was intended that Philipp would eventually succeed his father as Head of the House of Hesse, while his (younger) twin brother Wolfgang would be heir to the Finnish throne. The plans for a Finnish monarchy, however, soon came to an abrupt end with the defeat of Germany; Finland became a republic in July 1919.