The origin of rugby football is often credited to a young man named William Webb Ellis who "took the ball in his arms [i.e. caught the ball] and ran" while playing a form of football at Rugby school in 1823.

However historians have questioned the authenticity of this story, beginning with an official investigation by the Old Rugbeian Society in 1895. Nonetheless, the trophy for the Rugby World Cup bears the name of "Webb Ellis" in his honour, and a plaque at the school commemorates the "achievement."

From Wikipedia 

A rugby union team consists of 15 players: eight forwards, numbered 1 to 8, and seven backs, numbered 9 to 15[1]. Depending upon the competition, there may be up to seven replacements (substitutes or reserves). Professional rugby contains seven reserves, with a player being allowed to be substituted only once,