The Centaurus Cup, also known as the Southern Union Internationals, is contested by the senior men’s national teams of the eight nations of the Southern Union. Beginning in the 1906 season, it is the oldest international baseball tournament in the world. The championship is awarded every 5 years except in 1941 when it was not held because of the Second World War.
Development
In early-1903, Albaland business owner Tadd Steward proposed a tournament amongst the 8 nations situated in the South Indian Ocean with players representing their country. His idea of running a competition during the off-season had a lukewarm reaction from club owners who felt until one rulebook was decided upon, an international tournament would not be viable.
Upon the introduction of the Durand Rules for the 1905 season, Steward continue to propose a yearly international tournament akin to the British Home Championship; a competition for association football between the United Kingdom’s four national teams: England, Scotland, Wales, and Ireland.
With four nations not even having a professional competition at the time (Albaland, Le Grout, Novainsula and Zuidgelders), head of the Ianoian Baseball Association Ambrose Cavanagh suggested limiting the tournament to countries with professional leagues only, something that was ratified during a meeting on the 8th November 1905.

Despite the backing of fans, journalists and even governing bodies for baseball in Günsovölk, Houtmansland, Ianoia, and Koana Islands, many team owners were worried the competition would be a failure, suggesting that the poor competition would turn people off club baseball and affect the profits of clubs across the Southern Union.
During a meeting on 8th of November 1905, the first Centaurus Cup was formally agreed upon, albeit as a one-off ‘trial’, to be contested between Günsovölk, Houtmansland, Ianoia, and Koana Islands in November of 1906 with all games being played in Omfattandestad’s Gothica Stadion.
The tournament was to be called Centaurus Cup after Centaurus, one of the largest constellations in the sky. Centaurus also has the greatest number of visible stars out of the southern hemisphere constellations and contains two of the top 10 brightest stars in the sky – Alpha Centauri and Beta Centauri. In mythology it is most often associated with the myth of the Centaur (the half man, half horse creature).
Moving Forward
With most team owners and even players believing the competition to be a failure, and regarded suspiciously as a show rather than a competition, no further tournament was organised until Tadd Steward pushed for the tournament to become at least biennially following the financial success of the 1906 event. On 24th on June 1908, with the vocal backing of fans and journalists who were crying out for another tournament, the national governing bodies formally agreed to organise the Cup every 5 years under the new South Indian Ocean Baseball Association (SIOBA) and that any nations within the South Indian Ocean running professional competitions may enter.
Tadd Steward acted as the first general secretary until his death on the 23rd of April 1911, seven months prior to the second tournament.
Format

Prior to Le Grout entering the Centaurus Cup in 1951, each team played each other twice in a round-robin tournament throughout the month of November. For the first 4 tournaments, the winner was the team that finished top of the standings and from 1926 to 1941 the top three teams entered into play-offs, with 2nd and 3rd place playing a one-off game to determine who met the 1st-placed team in the Final. The tournament uses the Durand Rules with two points for a win and 1 for a draw.
When Le Grout entered the competition in 1951, the format changed to what is still in use today. The 8 nations are seeded into two pots based on SIOBA rankings (total Win and Draw points from last two tournaments, plus 4 for winning a tournament and 2 for making the play-offs). The teams are then drawn into two groups of 4 where they play teams within their group twice and the teams from other group once for 10 games each in total. The top two teams from each group play each other with the winner progressing to the Final.