Portsmouth FC was formed by five local businessmen in April 1989 to preserve first class football in the town after the Royal Artillery FC was forced to disband having breached the strict rules on amateurism of the period. The new club joined the Southern League in 1899 finishing runners-up in their first season and winning the title in 1902.   In 1911 Portmouth sufffered a severe financial crisis – a recurring theme in the club’s history - and the club was wound up after suffering relegation to the Southern League Second Division. A new limited company was promptly formed to take over and the club was saved after substantial guarantees were offered by the new board of directors.In 1920 the First Division of the Southern League was incorporated into the Football League as the Third Division. Promoted to the Second Division in 1924, Portsmouth performed well winning promotion in the 1926-27 season.  Having established themselves in the top flight, the 1938-39 season saw Portsmouth win the FA Cup defeating favourates Wolves  4-1. League football was suspended due to the Second World War, meaning Portsmouth hold the unusual distinction of holding the FA Cup for the longest uninterrupted period because the trophy wasn't contested again until the 1945-46 season. League football resumed for the 1946-47 campaign. During the 1948-49 season the club were tipped to be the first team of the 20th century to win the Football League and FA Cup double. However, Pompey crashed out of the FA Cup in the semi-final against Leicester City, but made up for it by claiming the league title. The club retained the title the following year, beating Aston Villa 5-1 on the last day of the season.   Although Portsmouth finished third in 1954-55, subsequent seasons saw them struggle and they were relegated to the Second Division in 1959.  Portsmouth went down to the Third Division in 1961 (the first former English League champion team to do so) but were promoted back to the Second Division at the first time of asking.  They were relegated to the Third Division in 1976 and by November of that year were on the verge of bankruptcy. With players having to be sold to ease the club's financial situation, and no money available for replacements, Portsmouth were relegated to the Fourth Division in 1978.  They were promoted back to Division Three in 1980, and in the 1983 season they won the Third Division championship  gaining promotion to the Second Division.  Promotion to the First Division was secured in 1986-7 under Alan Ball.  Unfortunately, by the middle of the 1987-88 season the club was again in grave financial trouble, and Portsmouth were relegated straight back to the Second Division. 

Portsmouth's centenary season, 1998-99, saw a serious financial crisis hit the club, and in December 1998 Portsmouth went into financial administration. Milan Mandarić saved the club with a takeover deal in May 1999.  The arrival of Harry Rednapp in 2002 saw a major revival in the club’s fortunes. Portsmouth finished top as First Division champions on 27 April 2003, six points clear of second-placed Leicester City, gaining promotion (with a game to spare) to the FA Premier League, returning to the top tier of English football after an absence of fifteen seasons. This time the club consolidated its position in the top tier of English football.  Rednapp left the club briefly to manage Southampton but returned to take Portsmouth to the FA Cup Final in 2008, which they won by beating Cardiff 1-0.  On 25 October 2008, Redknapp left Portsmouth for a second time, this time to join Tottenham Hotspur as their new manager. The club’s fortunes on and off the field declined and a series of takeovers left the club with the unwanted distinction of being the first Premier League club to enter administration in February 2010.  Portsmouth were relegated but managed to reach the FA Cup final against Chelsea which they lost 0-1. Two seasons later (2011-12) they were back in adminstration with debts of £58m. The season ended with the club relegated to the third tier of English football followed by relegation at the end of the following season to the fourth tier of the English football league system for the first time since the late 1970s. After winning the League Two divisional championship title in the final game of the 2016-17 season, Portsmouth became only the fifth English football club to win all four tiers of current English professional football (after Wolves, Burnley, Preston North End, and Sheffield United). In addition, Portsmouth are also one of only two English football clubs to have been champions of five professional divisions including the former regional Football League Third Division South championship in the 1923-24 season. Wolverhampton Wanderers also share this distinction.