Born in Melrose at Dalkey, County Dublin, Doyle expressed an interest in religious service and soldiering from a young age. Born in modest circumstances to a large family, William was the youngest of seven children. Frail and prone to illness in youth, the lad overcame fragility of health and made his decision to enter the Jesuit ministry.

From his earliest years in study of the Bible, Doyle demonstrated an immense aptitude for the holy scriptures and the principles of the Lord Jesus. His priesthood was marked by frequent writings on Christian subjects - much of this was published during his life, while other poignant notes were compiled into collections. All display clear, commonsense spiritual advice, as well as excursions to wit and liveliness that serve to make Father Doyle's counsel all the more valuable.

Father Doyle's boyhood dream of becoming a soldier was answered when, in 1914, war broke out in Europe. He enthusiastically enlisted as a chaplain in the British Army, and was promptly sent to the Western Front in France, where he bore witness to the carnage of trench warfare. By all accounts Doyle's strength of spirit remained; he was popular in his unit, and saved several of his comrade's lives - many considered Doyle to have divine protection. Yet his death was sudden; an exploding shell ended his life, at the age of only forty-four.