Peter was one of several sons of Bernard and Euphemia Murphy who lived at Emmaville NSW where his birth was registered in 1891. The family later moved to Copeton where Peter attended the local school.
At the age of twenty five, Peter enlisted at Inverell in September 1916. At the end of that month he was one of twenty four men given a public farewell at the Town Hall and presented with an Inverell medal and a pair of socks. Peter joined the 34th Battalion, 6th Reinforcement and sailed from Australia on HMAT A72 Beltana in November 1916.
After arriving in England at the end of January 1917, further training took place. He was ill with pleurisy in April and did not go to France until March 1918. Just eighteen days later he was reported missing in action, later confirmed as killed in action at Villers-Bretonneux on 6 April 1918. Private Murphy was buried at Crucifix Corner Cemetery, Villers-Bretonneux, France. His identity disc was returned to his Mother.