Born in Quetta, British India (now Pakistan) to a military family, Dennis Eagan was educated at Gresham’s School and followed his father’s footsteps and had a distinguished career in the Royal Engineers, retiring as a Colonel. As a captain of the Combined Services and Army hockey team, he was selected to the 1952 British Olympic team, where he played in all three matches and won a bronze medal. In all, Eagan was capped 8 times with the British team.
After retiring from active playing, Eagan coached the Singapore national team then served as secretary and secretary-general of the British Hockey Association from 1976-86. In 1986 he was heavily involved in the organization and running of the World Cup in London. In 1987 he was appointed vice-president of the British Hockey Association. Eagan was also the chairman of the Army Hockey Association, secretary of the European Hockey Association, and treasurer and then vice-president of the British Olympic Association.