May 23, 2015: Supporters of same-sex marriage celebrate in Dublin as votes in the referendum are counted.Getty Images

On May 22, 2015, nearly two million people in Ireland went to the polls to cast their vote in a Marriage Equality referendum.

Voters were asked if they agreed with the proposal to amend Article 41 of the Irish Constitution to provide that two persons may marry without distinction as to their sex.

The referendum question noted that marriage would continue to be regulated by legislation and the common law.

"The Thirty-fourth Amendment of the Constitution (Marriage Equality) Bill 2015 proposes to insert the following section after section 3 of Article 41 of the Constitution: 4. Marriage may be contracted in accordance with law by two persons without distinction as to their sex."

1,949,725 people in Ireland voted, and 1,201,607 - or 62.07% - voted in favor of amending the Irish Constitution to provide for same-sex marriage.

In doing so, Ireland became the 19th country in the world to approve same-sex marriage - and the first to do so by popular vote.

May 22, 2015: Ireland votes 'yes' on marriage equality. (RollingNews.ie)

It was a long road to get to the successful vote, which came just under 22 years after Ireland passed legislation that ended the criminalisation of homosexuality in June 1993.

Despite homosexuality being decriminalized in 1993, it was 2010 before the Civil Partnership Bill passed through Cabinet, which granted same-sex couples some of the same rights as married couples.

The Act broadly gave same-sex couples the same rights as married couples. However, it did not change or adapt the law on issues relating to children, such as custody, guardianship, and adoption.

In July 2012, a Convention on the Constitution was approved by Resolution of both Houses of the Oireachtas. Among the eight topics the Convention was asked to consider was same-sex marriage.

The Convention’s membership comprised 66 randomly-selected citizens, 33 politicians from both Houses of the Oireachtas and the Northern Ireland Assembly, and an independent chair.

The Convention considered same-sex marriage in its third plenary meeting in June 2013 and ultimately recommended that yes, the Irish Constitution be changed to allow for civil marriage for same sex couples. The Convention further favored directive or mandatory wording in the event of such amendment going ahead.

That November, the Irish Government agreed that a referendum should be held no later than mid-2015 on the question of enabling same-sex couples to marry.

In January 2015, the Thirty-fourth Amendment of the Constitution (Marriage Equality) Bill 2015 was introduced in the Oireachtas and, following debates, was approved in both the Dáil and the Seanad in March.

In February 2015, then-Taoiseach Enda Kenny announced that the same-sex marriage referendum would be held on May 22 that year.

The four main parties in the Dáil at the time - Fine Gael and Labour, who were in a governing coalition, and Fianna Fáil and Sinn Féin - all supported the 'yes' vote.

Meanwhile, the 'Yes Equality' umbrella group was established by the Gay and Lesbian Equality Network (GLEN), Marriage Equality, and Irish Council for Civil Liberties. Similarly, the 'Business for Yes Equality' umbrella group saw more than 150 companies signal their support for a yes vote.

May 16, 2015: Posters in Dublin's City Centre calling for a 'yes' vote in the same-sex marriage referendum. (RollingNews.ie)

There were also groups that called for a 'no' vote, including Mothers and Fathers Matter, First Families First, StandUp4Marriage, and Mandate for Marriage.

May 19, 2015: Campaigners calling for a 'no' vote on Dublin's Grafton Street ahead of the referendum. (RollingNews.ie)

Notably, the #HomeToVote campaign was conceived for the 2015 referendum (and was later used in the 2018 abortion referendum). As per Irish law, Irish citizens retain their right to vote in Irish elections for only 18 months after taking residence in another country, and postal voting is largely not permitted. As such, many emigrants flocked home to vote in the referendum, chronicling their journeys under the #HomeToVote hashtag. So popular was the hashtag that it ranked fifth amongst Twitter’s top news trends in 2015.

Finally, on May 22, 2015, Ireland went to the polls. Counting began at 9 am the following day, and early tallies projected a landslide victory for the 'yes' campaign.

The early tallies were correct. Ireland voted 62.07% to 37.93% to provide for same-sex marriage in the Irish Constitution. Every constituency except for one (Roscommon–South Leitrim) voted in support of the amendment.

Afterward, the referendum faced two legal challenges, but they were ultimately thrown out.

The Marriage Bill 2015 - which implements the constitutional obligation in Article 41.4, which was inserted into the Constitution as per the referendum - was introduced in September and was signed into law on October 29, 2015.

The Act came into force on November 16, and Ireland's first-ever legal same-sex marriage was held the following day in Clonmel, Co Tipperary.

Same-sex marriage in Ireland since the 2015 referendum

Marking the tenth anniversary of the historic referendum, Ireland's Central Statistics Office (CSO) published data on same-sex marriages.

“The CSO has collected data on same-sex marriages as part of our Vital Statistics releases since that historic vote," Seán O’Connor, Statistician in the Life Events and Demography Division, said.

"Between November 2015 and 2024, we can see that 5,956 same-sex marriages were celebrated in Ireland.

"Of these, 3,178 involved male marriages and 2,778 were female marriages.

"Overall, same-sex marriages accounted for 3.3% of total marriages annually since 2016.

"July and August were the most in-demand months for same-sex marriages from 2016 to 2024, while Friday led the way as the most sought-after day to tie the knot.

"Civil ceremonies were the most popular form of ceremony for nearly two-thirds (63.7%) of same-sex couples.”