Northern Ireland

On 18 February 1882, 15 months after the founding of the Irish FA, Ireland made their international debut against England, losing 13–0 in a friendly played at Bloomfield in Belfast. This remains the record defeat for the team, and also England's largest winning margin. On 25 February 1882, Ireland played their second international, against Wales at the Racecourse Ground, Wrexham, and an equaliser from Johnston became Ireland's first ever goal.

In 1884, Ireland competed in the inaugural British Home Championship and lost all three games. Ireland did not win their first game until 19 February 1887, a 4–1 win over Wales in Belfast. Between their debut and this game, they had a run of 14 defeats and 1 draw, the longest run without a win in the 1800s. Despite the end of this run, heavy defeats continued. On 3 March 1888, they lost 11–0 to Wales and three weeks later, on 24 March, lost 10–2 to Scotland. Further heavy defeats came on 15 March 1890 when they lost 9–1 to England, on 18 February 1899 when they lost 13–2 to England and on 2 February 1901 when they lost 11–0 to Scotland.

In 1899, the Irish FA also changed its rules governing the selection of non-resident players. Before then the Ireland team selected its players exclusively from the Irish League, in particular the three Belfast-based clubs Linfield, Cliftonville and Distillery. On 4 March 1899, for the match against Wales, McAteer included four Irish players based in England. The change in policy produced dividends as Ireland won 1–0. Three weeks later, on 25 March, one of these four players, Archie Goodall, aged 34 years and 279 days, became the oldest player to score in international football during the 19th century when he scored Ireland's goal in a 9–1 defeat to Scotland.

In 1920, Ireland was partitioned into Northern Ireland and Southern Ireland. In 1922, Southern Ireland gained independence as the Irish Free State, later to become a republic under the name of Ireland. Amid these political upheavals, a rival football association, the Football Association of Ireland, emerged in Dublin in 1921 and organised a separate league and international team. In 1923, at a time when the home nations had withdrawn from FIFA, the FAI was recognised by FIFA as the governing body of the Irish Free State on the condition that it changed its name to the Football Association of the Irish Free State. The Irish FA continued to organise its national team on an all-Ireland basis.

Between 1928 and 1946, the IFA were not affiliated to FIFA and the two Ireland teams co-existed, never competing in the same competition. On 8 March 1950, however, in a 0–0 draw with Wales at the Racecourse Ground in a FIFA World Cup qualifier, the IFA fielded a team that included four players who were born in the Irish Free State. All four players had previously played for the FAI in their qualifiers and as a result had played for two different associations in the same FIFA World Cup tournament.

After complaints from the FAI, FIFA intervened and restricted players' eligibility based on the political border. In 1953 FIFA ruled neither team could be referred to as Ireland, decreeing that the FAI team be officially designated as the Republic of Ireland, while the IFA team was to become Northern Ireland.