Manchester United won the treble during the 1998/1999 season. They actually completed the treble in 1999 on 26 May when they won the UEFA European Cup.
In 1999, Manchester United won the League title, FA cup and the European Cup (champions league).
Manchester United Foot Ball club
They haven't the only club to achieve this are Manchester united.
May 5th 2008Manchester united did not win the champion league in 2008, they last won it in 1999 in Barcelona. That year they won the treble.
It was in 2008.
ey won the E.P.L.