Ciaran entered UCD in October 1933, having passed through Clongowes Wood College. He at once joined the College Boat Club and, in 1934, was a member of the Maiden Eight unbeaten that year.
Ciaran was an enthusiastic oarsman and he loved the sport for its own sake. He was also loyal to his club and he showed it by the manner in which he consistently gave of his best as a maiden then as a junior and finally, as a senior oarsman.
In 1937 he was elected Club Captain and in that capacity he showed his fitness not only as an oarsman, but also as a coach and an administrator. He threw all his energies into his work and during his Captaincy, to which he was re-elected in 1938, UCD Boat Club achieved a very high level of success.
For the first time the Club won the Wylie Cup and the Leander and Metropolitan Cups and Ciaran led it to outstanding victories including, the Senior 8+ IARU Challenge Cup for all Ireland (twice), and the north of England Head of the River Race at Chester. The sculling Championship of the Lee was a personal triumph for him. In all he won over 50 trophies.
Ciaran graduated in medicine and surgery in 1939 and shortly afterward went to England, where he joined the Royal Army Medical Corp on 12th October 1940. He was to die 3 1⁄2 years later, in March 1944, from wounds sustained in battle on a hill overlooking the small Indian town of Moreh on the India-Burma border.
In recognition of his services to rowing generally and particularly to UCD Boat Club, as well as tribute to his fine character and personality, his former associates and friends decided to perpetuate his memory by bringing to fruition the long contemplated and cherished plan for an annual race on the Liffey between UCD and Dublin University. For this race, a perpetual challenge trophy, to be known as the Gannon Memorial Cup was presented.
In 1947, the first Gannon Cup – Ireland’s version of the University Boat Race in England – was raced from Guinness’s Wharf, on the lower Liffey, down through the city to Butt Bridge.