From TheChels.info - The Chelsea Football Club Wiki
The London Combination was a league competition held during the First World War while regular football was suspended in Britain. It primarily included clubs from London (Chelsea, Arsenal, Tottenham Hotspur, Millwall, West Ham United, Fulham, Queens Park Rangers, Brentford, Crystal Palace and Clapton Orient), although sometimes teams from elsewhere in southern England, such as Portsmouth, Reading and Luton Town, also competed. Chelsea played in every edition of the tournament, winning it in 1915-16 and 1917-18.
After the war, the league was retained as a competition for the reserve sides of the major London clubs. In 1939 it was renamed the Football Combination. Chelsea's reserves won the league eleven times, in 1948-49, 1954-55, 1957-58, 1959-60, 1960-61, 1964-65, 1974-75, 1976-77, 1984-85, 1990-91 and 1993-94. Chelsea resigned from the league in 1999 to join the new Premier Reserve League.