The club was founded in the back garden of 12 High Street, Old Portsmouth on 5 April 1898 with John Brickwood, owner of the local Brickwoods Brewery as chairman, and Frank Brettell as the club's first manager.
The club joined the Southern League in 1899 and their first league match was played at Chatham Town on 2 September 1899 (a 1–0 victory), followed three days later by the first match at Fratton Park, a friendly against local rivals Southampton, which was won 2–0, with goals from Dan Cunliffe (formerly with Liverpool) and Harold Clarke (formerly with Everton).
That first season was hugely successful, with the club winning 20 out of 28 league matches, earning them the runner-up spot in the league.
1910–11 saw Portsmouth relegated, but with the recruitment of Robert Brown as manager the team were promoted the next season.
Football was anti suspended during World War I, but following the resumption of matches Portsmouth won the Southern League for the second time.
Continuing success saw them in the Third Division for the 1920–21 season.
They finished 12th that year, but won the division in the 1923–24 season.
The club continued to perform well in the Second Division, winning promotion by finishing 2nd in the 1926–27 season, gaining a record 9–1 win over Notts County along the way.
Portsmouth's debut season in the First Division was a struggle.
The next season they continued to falter, losing 10–0 to Leicester City, still a club record defeat.
However, despite their failings in the league, that season also saw Portsmouth reach the FA Cup final for the first time, which they lost to Bolton Wanderers.
Portsmouth managed to survive relegation, and their fortunes began to change.
The 1933–34 season saw Portsmouth again reach the FA Cup Final, beating Manchester United, Bolton Wanderers, Leicester City and Birmingham City on the way.
The club was again defeated in the final, this time to Manchester City.
Having established themselves in the top flight, the 1938–39 season saw Portsmouth reach their third FA Cup Final.
This time the club managed to defeat the favourites, Wolves, convincingly 4–1.
Bert Barlow and Jock Anderson scored whilst Cliff Parker scored twice (3rd and 4th) completed the famous victory.
League football was again suspended due to World War II, meaning Pompey hold the unusual distinction of holding the FA Cup for the longest uninterrupted period as the trophy wasn't contested again until the 1945–46 season.
League football resumed for the 1946–47 campaign. In Pompey's Golden Jubilee season of 1948–49, 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 in spectacular fashion. That season also saw them record a massive attendance of 52,385, a club record which still stands to this day. The club powered their way to the title the following year, beating Aston Villa 5–1 on the last day of the season, and are thus one of only five English teams to have won back to back titles since World War II. In 1956 Portsmouth played the first league game under floodlight against Newcastle United on the 22nd of February. Although the team finished third in 1954–55, subsequent seasons saw Portsmouth struggle and they were relegated to the Second Division in 1959. Portsmouth went down to the Tird 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 under the guidance of George Smith. Despite limited financial means, Smith maintained Portsmouth's Second Division status throughout the sixties until moving upstairs to become General Manager in April 1970.
A cash injection, that accompanied the arrival of John Deacon as chairman in 1972, failed to improve Portsmouth's league position.
With Deacon unable to continue bankrolling the club on the same scale, Portsmouth were relegated to the Third Division in 1976.
In November 1976 the club found itself needing to raise £25,000 to pay off debts and so avoid bankruptcy.
With players having to be sold to ease the club's financial situation, and no money available for replacements, Portsmouth were forced to rely on an untried manager, Ian St John and inexperienced young players.
Consequently, they were relegated to the Fourth Division in 1978.
Portsmouth were promoted back to Division Three in 1980, and in the 1982–83 season they won the Third Division championship, gaining promotion back to the Second Division.
Under Alan Ball's management, Portsmouth narrowly missed winning promotion to the First Division twice before finally succeeding in 1986–87.
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.
The summer of 1988 saw Deacon sell the club to London based businessman and former Queens Park Rangers Chairman, Jim Gregory.
Jim Smith's arrival as manager at the start of the 1991–92 season, combined with the emergence of some good young players, sparked a revival in the team's fortunes and that year Portsmouth reached the semi-finals of the FA Cup, losing on penalties to eventual winners Liverpool after a replay.
Portsmouth missed out on promotion to the FA Premier League only by virtue of having scored one less goal than West Ham United.
In the summer of 1996 Terry Venables arrived at Portsmouth as a consultant, later taking over as chairman after buying the club for £1.
The team enjoyed a run to the quarter-finals of the FA Cup in 1996–97, beating FA Premier League side Leeds United en route, but finished just short of the qualifying places for the play-offs for promotion to the Premier League.
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, and the new chairman immediately started investing.
However the club only survived on the last day of the 2000–2001 season when they won their final game and Huddersfield Town lost theirs, keeping Portsmouth up at their expense.
Some say the sheer noise from the Fratton End that day almost halted the away teams attacks.
Harry Redknapp took over as manager in early 2002, with Jim Smith returning to the club as assistant manager.
Redknapp was able to make the most of Mandarić's willingness to invest in players at a time when competitors were struggling after the collapse of ITV Digital's television deal with the Football League.
Just over a year later, Portsmouth were celebrating winning the Division One Championship and promotion to the Premier League, winning the title with a game to spare.
The club finished 13th, 16th and 17th in their first three Premier League seasons.
Redknapp had resigned midway through the club's second Premier League season, after a disagreement with Mandaric, and went on to manage bitter rivals Southampton, only to return just over a year later.
This was because the side who had hastily sacked the French manager Alain Perrin were languishing in the relegation places.
In January 2006, Portsmouth were bought by businessman Alexandre Gaydamak whose funding allowed for the club to buy practically a whole new squad mid-season.
The signings included a quartet from Tottenham Hotspur and the highly rated Argentina international Andrés D'Alessandro on loan from VFL Wolfsburg.
With large amounts of money available for the manager to make record signings, the club finished the 2006–07 season in the top half of the table for the first time, only one point short of European qualification.
The 2007–08 season started with Portsmouth beating Liverpool 4–2 on penalties to win the Barclays Asia Trophy after a goalless draw, with Pompey goalkeeper David James saving penalties from Yossi Benayoun and Fernando Torres.
It was not the club's only success that season; in Portsmouth reached the 2008 FA Cup Final for the first time since 1939.
They eliminated Manchester United at Old Trafford in the quarter-finals, with Sulley Muntari scoring the only goal from the spot past stand-in goalkeeper Rio Ferdinand after the dismissal of Tomasz Kuszczak, who earlier replaced the injured Edwin van der Sar, and the following day became the only Premier League team left in the cup, following Cardiff's surprise win over Middlesbrough.
Portsmouth immediately became favourites to win the cup; in a season noted for the scalping of favourites.
On 5 April, Kanu netted the winner as they beat Championship side West Brom 1–0 at Wembley Stadium in the semi-finals, co-incidentally the same day that the club celebrated its 110th birthday.
Portsmouth went on to win the cup with a 1–0 win against Championship team Cardiff City, with Kanu again scoring the only goal.
The win earned them a place in the 2008–09 UEFA Cup, the club's first time playing European football.
Their first UEFA Cup match resulted in a historic 2–0 victory over Vitoria Guimaraes and went on to win the aggregate (4–2).
This put Portsmouth in the group stages for the first time in their history.