The first football team known in Caernarfon was Caernarvon Athletic, formed in September 1876. Early in the 1890s, Athletic went out of existence, and in 1894 Caernarvon Ironopolis was formed. They competed in the North Wales Coast League for almost a decade until a dispute with the league caused the team to come to an end in 1903. This resulted in the formation of the Caernarvon Celts by some of the Ironopolis players. Others affiliated to the Caernarvon Royal Welch Fusiliers and both clubs played separately before amalgamating to form Caernarvon United in 1906.
Source
Welsh Premiership Football League website