In 1899 the Recreation Ground was opened and Jim Davies and other members of the old Harriers side got together to form the official town team. It had taken two years to transform the ground into a suitable sports site; built over two disused and filled-in pit shafts, volunteer labourers sweated and strained to get it ready. Tredegar helped form the Monmouthshire League, were admitted to the Welsh Rugby Union and became members of Monmouthshire County R.F.C, of which Jim Davies was one of the founders. Early Tredegar stars were Jim Hares, Will Evans, Ernie Bird, Enoch Hughes and Jim Davies but probably their finest product was Percy Jones, who won eight caps for Wales after he moved to Newport and was a member of Wale's "Terrible Eight" pack against Ireland in 1914. Percy Jones was a forward of tremendous physical physique and he was reputed to have the thickest legs in Gwent; so huge, that he had to have special rugby socks knitted for him as none of the standard sizes fitted. He was a also a big joker, and the tale is still told in Tredegar of how Big Percy and Jim Davies trimmed the local policeman's trousers above the knee while he dozed before going on duty.
Though Tredegar never won the Monmouthshire League before 1939, they claimed the runners-up spot. In those days, trainloads of supporters always traveled away with the Tredegar team. Once, in Bristol, they booked the entire seating capacity of the Bristol pantomime: two full trainloads made the journey. After the war, Tredegar's outstanding players were Dai John Vaughan, the flying wing, Steve Barr, rated one of the best uncapped fullbacks in Wales and the Davies brothers Edgar, Ivor and Jack, who they went elsewhere. It was not until after the Second World War that Tredegar won the Monmouthshire League and their feat of 1951 was repeated a couple of years later when they decided to pull out of the league; at the same time, they obtained permission to use the complete armorial bearings of Lord Tredegar as the club badge.