He was born to American parents, Montrose Wellington Irwin and Marion Reynolds Irwin in Rosario, Argentina in 1926. Irwin came to the United States in 1945 to attend Yale College. Soon after enrolling at Yale, he joined the United States Army, where he served with the Joint Brazil-United States Military Commission in Rio de Janeiro.
He was born to American parents, Montrose Wellington Irwin and Marion Reynolds Irwin in Rosario, Argentina in 1926. Irwin made his way to the United States in 1945 to attend Yale College. After enrolling at Yale, he soon joined the U.S. Army and served with a joint commission in Rio de Janeiro.