The FitzWarin family took its name from Guarine (or Warin) de Meez, said to have been a member of the House of Lorraine who came to England after the Norman Conquest. Fulk FitzWarin, the first baron, was the fifth of his family to bear the name Fulk, though some chronicles conflate two of his ancestors together. His father, Fulk (IV) FitzWarin, was appointed by King Richard I to defend the Welsh Marches, later rebelled against (and was outlawed by) King John, and, having made his peace with King Henry III, drowned in a river during the Battle of Lewes in royal service during the Second Barons' War. His grandfather was Fulk (III) FitzWarin.