William Scallon was born in Joliette Province, Quebec, in December 1855. His father, Charles Edouard Scallon, was a native Canadian of Northern Irish ancestry, who had served for a period in the United States Navy. His mother, Delia Trumble Scallon, was born in Ireland. Throughout his life, Scallon felt a deep loyalty and concern for Ireland. He attended Joliette Seminary, where he received a classical education, and was trained in law at McGill University, graduating in 1876. After several years of law practice in Montreal, Scallon emigrated to the United States, moving to Wickes, Montana, in 1883 and to Butte the following year. He served as general counsel for the Anaconda Copper Mining Company until 1900, when he was chosen to succeed Marcus Daly as president and western general manager of the company, during the tumultuous period known as the War of the Copper Kings. In 1904, he resigned as president of Anaconda to return to private practice. Scallon briefly left Montana from 1911-1913, to serve as chief counsel for the Union Pacific Railway in New York. On his return in 1913, he settled in Helena and joined in a law practice with T.J. Walsh and C.B. Nolan. This practice became one of the most prominent in Montana. In 1929, President Herbert Hoover appointed Scallon special counsel for the United States in a suit against the Standard Oil Company for the recovery of land within the Naval Oil Reserve in California. During his later years, Scallon served as one of the directors of the Thomas Cruse Mining and Development Company. Scallon was a Republican. He only held public office once, when he was elected to the 1907 State Legislature. However, he was active in various civic functions, including almost 70 years of membership in the Montana Bar Association, service on the Butte Civic League, and memberships in the Elks, the Knights of Columbus, and the Junipero Serra Club. He never married and, during his residence in Helena, lived at the Montana Club. William Scallon died July 5, 1951, in Helena.