Major Peter John Cashin (March 8, 1890 - May 21, 1977) was a politician and soldier from Newfoundland who played a major role in Newfoundland's roles in World War One, the Canadian Civil War, World War Two and eventually the Newfoundland Crisis. Cashin was the Minister of Defence for the Free State of Newfoundland during World War Two and eventually served dually as Minister and as Chairman of the Newfoundland State Defence Force. As the war wound to a close, he broke off from the War Government of Joey Smallwood and formed the United Newfoundland Party, becoming a key figure in the Newfoundland republican movement. His UNP won an unexpected majority in the 1946 general election called by Smallwood due to defections in the Assembly of Newfoundland from both the left and the right.