All good things come to an end, and the success that Manchester United experienced under Sir Matt Busby is no exception. Just before the 1970s, Busby stepped down as manager.
Busby accepted a role as director at the club following his managerial retirement, and this would signal the end of an era at the club, although his influence is undoubtedly still felt at Old Trafford.
Former United player Wilf McGuinness, whose son Paul is currently the under-18s head coach and Assistant Academy Director at United, was promoted from reserve team coach to be Busby's successor. In his first season at the club, United would only finish eighth in the First Division
McGuinness reached three semifinals during his brief tenure, but his reign at the club was ultimately without any trophies. In December 1970, McGuinness was demoted to reserve team coach and Busby briefly returned to his managerial duties.
Unfortunately, even Busby was helpless to stop the club from entering a period of decline. Busby led the club to another eighth place finish before Frank O'Farrell took over at the conclusion of the 1970-71 season.
With European glory now secured, United struggled to maintain their success. The "Holy Trinity" of George Best, Denis Law and Bobby Charlton would all suffer disappointing fates early in that decade following the European Cup.
Charlton, the man who had been the talisman of the club in aftermath of Munich, was 30 at the time of the European Cup triumph and age would soon catch up with him. United were suffering from an aging squad and found themselves in the relegation battle early in the new decade.
Tommy Docherty had taken over as the manager during the 1971-72 season, and it seemed that Charlton was not in his plans, although it is believed Docherty did not want to be the man who decided to part ways with the United legend.
After 758 appearances and 249 goals, Charlton retired at the conclusion of the 1972-73 season. He would remain the club's all-time appearance leader until the 2008 Champions League final when Ryan Giggs surpassed the record as United triumphed in Europe once again. Charlton's 249 goals is still the record at Old Trafford. He has served on the board of directors at United since 1984.
Best, plagued by personal demons off the pitch, would have his United career come to a premature end on New Year's Day 1974. In The Official Illustrated History of Manchester United, there is a fitting quote about Best: "It was Best's fate that the only opponent he could never elude was drink, but his place in the pantheon is reserved for all time in spite of his unfortunate demise."
This was the sad truth for Best and his career. He began missing training and at one point retired at the age of 26. He would return for the 1972-73 season shortly after his retirement, but his lifestyle would soon bring an end to his time at Old Trafford. After six seasons as United's top scorer, Best quit the club on January 1, 1974.
Best would spend the remainder of his career with brief spells at numerous clubs in a variety of countries. His alcoholism would eventually be his undoing. Best received a liver transplant in 2002, but continued to drink. Drugs prescribed to help his body accept the transplant resulted in kidney infection in October 2005. His condition continued to worsen until Best died at the age of 59 on November 25, 2005 from multiple organ failure.
Law, the final member of the trinity, was released by Docherty at the end of the 1972-73 season and then signed for Manchester City. He famously scored against United during City's final game of the 1973-74 season, but refused to celebrate believing his goal had relegated United. As it stood, United would be relegated to the Second Division regardless of the outcome of that match. He retired at the conclusion of that season.
Six years after winning the long sought-after European Cup, United had been relegated to the Second Division. They were quick to return to the First Division, however, winning the Second Division title in 1974-75, the club's first season after relegation. The club have not been relegated since.
In 1977, the club would rediscover success as Docherty led United to the FA Cup final where they triumphed 2-1 against Liverpool with goals from Jimmy Greenhoff and Stuart Pearson. Alex Stepney, the goalkeeper whose heroic save against Eusebio proved key in the European Cup final, was the only remaining member of that 1968 squad.
Docherty was dismissed from his role as manager soon after the FA Cup victory when it was discovered he had an affair with the wife of the club's physiotherapist. Dave Sexton replaced him as manager.
United booked themselves a place in the 1977 Charity Shield against league champions Liverpool as a result of their FA Cup success, but could only manage a draw, and the rivals shared the honor in the days before penalties decided the match. The club would finish 10th in the First Division that season.
The following season United would finish ninth in the league and made another run to the final of the FA Cup, where they lost 3-2 to Arsenal.
After more than two decades of incredible success under Busby, United suffered through a painful decade by comparison. Relegation, promotion and a solitary FA Cup success. After being at the peak of European football the previous decade, the 1970s would inevitably prove disappointing.
Fortunately, the man who would take United beak to the top in both England and Europe was also taking his first steps into management in the 1970s. Although with Aberdeen at the end of the 1970s, Alex Ferguson would come to Old Trafford the following decade to begin a period of unrivaled success.
Second Division: 1974-75
FA Cup: 1976–77
FA Charity Shield: 1977