Eleven years before the Soccer authorities held the first World Cup in Uruguay in 1930 Rugby promoted their first World Event in the form of the Kings Cup in 1919
Most think that the first Rugby World Cup took place in 1987 but that is not strictly true as was revealed in Stephen Cooper's recent book "After the Final Whistle"

Tensions had developed between the RFU ,the other home unions and the dominions during and just after WW1 and it was felt that this had to be addressed

Sports historian Tony Collins takes up the story

The Kings Cup unveiled
The RFU's authority was consolidated in March and April 1919 when, apparently at the request of the War Office, it staged a sixteen match Inter-Services Tournament featuring representative sides from the Dominions and the services which became known as the ‘King’s Cup’. The tournament - which was the biggest international rugby union tournament staged anywhere in the world until the sport’s first world cup in 1987 - was explicitly designed to capitalise on the popularity of services rugby union during the war years, and became a celebration of rugby union’s past and a signal of future intent. It also had a broader, political motive, as The Times rugby union correspondent noted in March 1919:
It is a most practical means of continuing and strengthening the bonds of interest between us and our relations scattered over the world. War has brought all parts of the Empire closer…. Often in the past the ties between this country and the colonies have been slender, and the strongest of them is the common interest in British games.
As well as the Mother Country, the participating teams consisted of Australia, New Zealand, the Royal Air Force, South Africa and Canada - who were there for ‘missionary’ purposes to popularise the game in North America - competing in a league table with matches being staged across Britain at Swansea, Portsmouth, Leicester, Newport, Edinburgh, Gloucester Bradford and Twickenham, which staged six matches, including the final play-off.
 
Glasgow Accies first post WW1 captain R.A. Gallie played represented The Mother Country in what was effectively Rugby's first World Cup.
Gallie went on to be capped eight times for Scotland in 1920-21 and he heralded in an era of great success for Glasgow Accies