Daly and his fellow Irish volunteers would eventually be placed in the Connolly Column, part of the Lincoln Battalion of the XV International Brigade and saw action beginning in 1937. He served as a section leader and company commander in the 20th Anglo-American Battalion of the 86th Mixed Brigade formed in March 1937. Because of his previous experience in both the Irish civil war and as part of the British army, Daly was used as an officer, rising quickly through the ranks, becoming a Captain after the Battle of Brunete. His was 'a popular appointment'. Daly and his comrades would see action in the Battle of Pozoblanco as well as at Guernica before taking part in the Battle of Jarama and then fighting in the Aragon Offensive.