The appointment of Herbert Chapman in the summer of 1925 arguably shaped Arsenal into the football club it remains today.
The Englishman was tempted from his successful Huddersfield Town side by Arsenal chairman Henry Norris but despite immediate success in leading the Gunners to a second place finish in the First Division in 1925/26, the rest of the 1920s were spent in mid-table obscurity. Chapman did take the Club to their first FA Cup Final in 1927 but saw his side lose 1-0 to Cardiff City.
Despite Arsenal's league struggles Chapman persisted and by the early 1930s his hard work was bearing fruit. His innovative tactics, plus shrewd signings like David Jack, Cliff Bastin, Alex James and Eddie Hapgood transformed Arsenal into one of the most feared sides in the country.
Chapman's first trophy came in 1930 when Arsenal saw off his old employers, Huddersfield, in the FA Cup Final. The triumph offset a decade in which Arsenal would be the dominant team in English football. The Gunners won their first top flight title in 1930/31, repeating the feat two years later. Tragically it would be Chapman's last success.
In January 1934, the Arsenal boss died suddenly from pneumonia at the age of 55. He missed seeing the side he had moulded lift three back-to-back titles.
Aside from his achievements with the Gunners, Chapman has been remembered for the lasting effect of his innovations on both Arsenal and the game itself.
Among his revolutionary ideas were the use of the penalty area semi-circle, goal judges and a second referee. He also promoted the use of floodlights, oversaw the development of an electronic turnstile, developed a PA system which passed team news onto fans and created a letter and number scoreboard which was widely copied throughout the country over the next 50 years.
Furthermore Chapman was behind the famous Highbury clock, Arsenal's white sleeves - which he believed allowed players to identify each other more easily - feeder clubs and European tours. But perhaps his greatest invention was the 3-2-2-3 WM formation. It proved so successful in nullifying opponents that many English sides later adopted it, changing the domestic game as a spectacle.
Chapman used it to keep the Highbury faithful spellbound and lay the foundations for the Arsenal which has since continued to sit among the upper echelons of the game.