At the start of 1918, a lethal strain of influenza swept through the global population, eventually infecting up to half a billion people and claiming the lives of anywhere between 50 and 100 million.
Few countries were immune to devastating dangers of the Spanish Flu, with Ireland badly hit by the illness.
Around 20,000 people died on these shores in the period between 1918 and 1919 when it was at its height.
Then - as we are witnessing now with the spread of COVID-19 - society was forced to implement dramatic and strict changes. The sporting calendar was hastily redrawn all over the world as governments tackled the pandemic by clamping down on events that would potentially draw large numbers of people into enclosed spaces.
In Ireland, the GAA were forced to think fast.
While schools and libraries were closed, mass gatherings were also put on hold, with all football and hurling games either postponed or completely cancelled.
On 16 February 1919 Wexford beat Tipperary 0-05 to 0-04 at Croke Park to lift the Sam Maguire. The game had been postponed from the autumn of 1918 as the flu swept through the country but even as its impacted relented, the consequences were grimly apparent. The Premier were without their top scorer Davy Toibin that day because he was too sick to play.
One quirk among that dreadful period was the huge success of Gaelic Sunday on 4 August 1918, a countrywide act of defiance to the British crackdown on all GAA activities.
Over 50,000 people across Ireland played Gaelic games in a peaceful, organised protest that Sunday, an act that ultimately saw an end to the requirement of a license to play a GAA match.
That famous day came in between two devastating waves of the Spanish flu, which took many lives during a mild spring, eased off, and then came back with a vengeance in a traumatic autumn/winter period.
Across the water meanwhile, competitive football had been suspended because of the war.
The Football League and FA Cup did not take place during the period between 1915 and 1919, with regional league competitions set up to give those interested some sort of outlet.
These competitions did produce champions from the Lancashire, Midlands, London and Northern division which were played over the course of 1918/19.
The 1920 Summer Olympics in Antwerp was not affected by the flu, which had all but disappeared by then.
But in the USA, there was serious concern about big gatherings for the popular sporting events of the day.
College football games were cancelled in several of the major cities, while in Major League Baseball a slew of high-profile players died after contracting the Spanish Flu.
Babe Ruth reportedly caught the disease but recovered.
In ice hockey, the 1919 Stanley Cup, for the first and only time to date, had no declared champion.
The play-off series was axed after five games. The Seattle Metropolitans were due to face the Montreal Canadiens in the deciding game of the series, but when several of the Canadiens players and their manager George Kennedy were stricken with the flu, the game was scratched.
One player, Joe Hall, later died, while Kennedy suffered complications which ultimately led to his passing in 1921.
And in boxing, a much-hyped heavyweight six-rounder between Jack Dempsey and Barney Lebrowitz (aka Battling Levinsky) was postponed, though it eventually took place in Philadelphia, in November 1918.
At that point many cities had started to relax regulations forbidding large crowds gathering in one area, and a sizeable audience witnessed Dempsey flatten his opponent with a fierce right-hander in the third.