O’Flaherty was born in County Cork, Ireland, in 1898. He was ordained a priest in 1925 and earned doctorates in divinity, canon law, and philosophy. His intellect and diplomatic skills quickly caught the attention of the Holy See, leading to postings in Egypt, Haiti, and Santo Domingo. By 1934, he returned to Rome to work in the Holy Office. When World War II broke out, O’Flaherty initially visited prisoner-of-war (POW) camps in Italy to check on the welfare of prisoners. When Italy switched sides in 1943, thousands of British and Allied POWs escaped. Many made their way to Rome, seeking sanctuary.