The Cup Winners' Cup success in 1971 was the club's first silverware on the European stage.
After a 1-1 draw in the initial match two days previous in which Chelsea had let the lead slip at the death, Dave Sexton's men and Real Madrid faced off again in the replay in Athens to decide who would go home with the trophy.
The majority of Blues supporters who had been at the first game were unable to enjoy the triumph as they had to make use of their return flights, but those that did stay on weren't to be disappointed.
First-half goals from John Dempsey and Peter Osgood (who had scored in the original match) put Dave Sexton's men firmly in the ascendancy, but when Sebastian Fleitas scored for the Spanish side with 15 minutes remaining it made for an uncomfortable finish.
The Blues did manage to hang on though, sparking joyous scenes inside the stadium and even larger scale celebrations back in London.
The campaign had begun comfortably with a 6-2 aggregate win over Greek minnows Aris Salonika, before beating CSKA Sofia 1-0 home and away ensured a scare-free passage into the quarter-finals.
Having been paired with the Belgian side Bruges, most Blues fans were fairly confident of progressing. The first leg turned into a nightmare, however, and we returned to the capital with a 2-0 deficit.
Stamford Bridge was at bursting point for the return leg and the supporters more than played their part in pulling through an ill-tempered match. Peter Houseman scored early on before a late Osgood strike sent the match into extra time.
As Chelsea threw everything at the Belgian side, Osgood scored his second of the game and Tommy Baldwin scored a fourth to cap a memorable night.
The semi-finals threw up an all-English affair with us drawing Manchester City to see who would be making the trip to Athens for the final.
There was little to choose between the teams in the first leg at Stamford Bridge, but a solitary Derek Smethurst strike ensured we headed north for the return with a 1-0 lead.
The decisive game at Maine Road was another cagey encounter, but when City's goalkeeper Ron Healey put through his own net to give us a 2-0 aggregate lead, it left the home side with too much to do and we saw the game out to secure our place in the final.