[1] Taking on and matching full-forwards like South Melbourne's Bob Pratt (whom Regan regarded as his most difficult opponent),[2] Carlton's Harry Vallence, Richmond's Jack Titus and St Kilda's Bill Mohr, Regan earned his title as the "Prince of Full-backs".

He recovered in time to play a part in Collingwood's finals campaign, but again for the second successive year was on the losing end as Carlton emerged victorious with the 1938 pennant.

In January 1942 Regan announced his retirement from football to join the Salesian community at Sunbury as a lay brother.

[6] In February 1943, with Australia now involved heavily in the Second World War, Regan enlisted with the Royal Australian Air Force (RAAF)[7] and served as a leading aircraftman.

In April 1946, shortly after being discharged from military service, Regan returned to Collingwood and trained so well[8] that he was selected for their Round 1 match of the 1946 season against Hawthorn.