John Joseph Monaghan, one of 13 children, was born on 21 August 1918 at 23 Lancaster Street, Belfast and, after marrying Frances Thompson in 1938, he moved to Little Corporation Street, in the Docklands area of the city. He was only 11 when he began taking part in street boxing contests and by the time he was fourteen he was picking up a few shillings for victories. At this point he started training in a gym in Hardinge Street and was on the way to a professional boxing career.
Monaghan's career was interrupted by wartime service in the Navy but in November 1945, out of uniform and back in full training, Monaghan knocked out Eddie 'Bunty' Doran to win the Ulster flyweight title. In March 1948, there followed the highpoint of his career when he knocked out his old adversary, Patterson, in the seventh round of a fight at the Kings Hall to become the undisputed British, Commonwealth and World flyweight champion and the first Northern Ireland boxer ever to hold a world title. Monaghan later claimed that the clinching factor in his pre-fight preparations had been a diet of goat's milk and raw eggs. He used to walk Beauty the goat in the countryside outside Belfast where he did his training. In April 1949 he retained his world championship and won the European flyweight title when he defeated Maurice Sandeyron in Belfast and the following September, although he could only draw with Terry Allen in Belfast, he held on to his titles.
By this time, Monaghan had suffered from health problems and in April 1950, aged 32, he was forced to renounce his titles and retire undefeated. Although he some money from his boxing, it was quickly dissipated due to mismanagment forcing him to work successively as a taxi driver, lorry driver and a petrol pump attendant. In his last job at the Shamrock filling station, a queue of cars used to form as everyone wanted to have a chat with Rinty. He is buried in the Belfast City Cemetery beneath a headstone with the inscription ‘Undefeated World Flyweight Champion’ and in 2015 Rinty Monaghan’s was erected in Belfast to honour his legacy.