He married Anna (1552–1632), daughter of Duke Wilhelm IV "the Rich" of Jülich-Cleves-Berg, in 1574 and used the marriage as the basis of his claim to inherit the duchies in the succession controversy against the Elector of Brandenburg after William IV's only son, John William, died without heirs.

In 1613 Philip Louis's eldest son, Wolfgang Wilhelm, converted to Catholicism and gained the support of Spain and the Catholic League, while Brandenburg received the support of the Netherlands.

[citation needed] The conversion of his son and heir was very difficult for the staunchly Lutheran Philipp Ludwig.

By the Treaty of Xanten in 1614 the duchies were partitioned following the War of the Jülich Succession, with Wolfgang Wilhelm receiving the Duchies of Jülich and Berg.

Philipp Ludwig married Anna of Cleves (1 March 1552 – 6 October 1632), daughter of Wilhelm, Duke of Jülich-Cleves-Berg on 27 September 1574 and had the following children: