He went on to the Royal Military Academy Sandhurst in 1930. He continued to box there and was also noted for his horsemanship, originally learned from his father and honed while hunting in Ireland and Herefordshire. Despite the harsh discipline at Sandhurst, he managed to lead a hectic social life in London. In 1931 he was commissioned in to the Lincolnshire Regiment and served in the East in India and China. India especially gave him the opportunity to hunt, play polo, go pig-sticking and shoot. He had one of the highest handicaps at polo in India and China during his time there and regularly played against the American army in the Philippines; in China he owned and trained horses, one of which, Kilrea, won several races in Hong Kong. A wild and spirited young man with an eye for the girls, he enjoyed Army life in the East to the limit and often beyond. In the Second World War, O'Conor saw action at Dunkirk, however he saw no further action due to a training accident involving a grenade. However, he continued in the military in a training and administrative capacity. He retired with the rank of Major in 1946 and moved to live in Roundwood, Co Wicklow, where his father had bought a farm. He was not well off and he abandoned farming to become a representative for a firm that sold tractors to farmers. Later he became a dedicated inspector for the Society for the Prevention of Cruelty to Animals. Field sports were an important to him all his life. He hunted foxhounds, beagles, Otterhound and Basset Hound at various times. He was a former Master of DelganyBeagles, a popular pack among university students. He became an acknowledged expert on hounds of all types - and was asked to judge at various shows throughout Ireland and occasionally in England. His love of dogs and his way with them was legendary. In the Early 1970's he moved to Dún Laoghaire in Dublin. O'Conor succeeded as O'Conor Don on the death in 1981 of his second cousin, Father Charles O'Conor, the former provincial of the Jesuit Order in Ireland. Whereas the Jesuits in their austere way had insisted that Fr. O'Conor not call himself O'Conor Don, Denis O'Conor acclaimed the title with relish, and enjoyed its prerogatives to the full. However, Denis was not to inherit the family estate of Clonalis outside Castlerea, Co.Roscommon. He became chairman of historical and genealogical societies, a regular presiding presence at community events and was even involved in tourist promotion. He was founding member of the Council of Irish Chieftains, consisting of the descendants of the few princely families whose pedigrees have been authenticated by the Chief Herald of Ireland. He used his position to promote an interest in Irish heritage from genealogy, local history to archaeology. He became President of the Dún Laoghaire Genealogical Society in 1991 and President of the Genealogical Society of Ireland in 1999. He was also Deputy Chairman of the Standing Council of Irish Chiefs and Chieftains.
Personal Life
He married, in 1936, Elizabeth Marris, daughter of Rev. Stanley Punshon Marris, and had Issue:
Desmond Roderic O'Conor, a banker, formerly of Schroders and then Regional director of Kleinwort Benson for South America, who was married on the 23rd of May 1964 to Virginia Williams, daughter of British Diplomat Michael S. Williams and had issue.
His marriage to Elizabeth did not long outlast the birth of their only son. Elizabeth subsequently married James Cameron. O'Conor then married, in 1943, Rosemary O'Connell-Hewett, daughter of Capt. James Pearse O'Connell-Hewett and a great grand-daughter of Daniel O'Connell, the 19th-century Irish Liberator, and had issue:
Kieran Denis O'Conor, a Senior lecturer in Archaeology in NUI Galway, who was married on the 26th of August 1988 to Karena Mary Morton, and had issue.
Rory Dominic O'Conor, who was married on the 21st of August 1999 to Cecilia Emily Gleeson, and had issue.
A daughter, Gail, died aged thirteen.
Because he was divorced, O'Conor was precluded from following the family tradition of becoming a member of the Order of Malta but he joined and eventually became Grand Prior of the Irish priory of the Oecumenical Order of St Lazarus of Jerusalem, which contributes to the relief of leprosy. His own charitable impulses found a practical outlet in teaching disabled children to ride. The O'Conor Don died on the 10th of July 2000 aged 88 and was buried at the family plot in Castlrea graveyard on the edge of the family estate. His eldest son, Desmond, who lives in Sussex, succeeded as O'Conor Don.
