As part of her historic trip to the Republic of Ireland, Queen Elizabeth has made an appearance at Croke Park in Dublin, the sports field that was the site of a massacre of Irishmen by British troops 91 years ago.

During the Irish War of Independence, in Nov. 21 1920, British forces opened fire at a Gaelic football match at Croke, killing 13 fans and one player. These killings were allegedly retaliation after 14 suspected British intelligence agents has been assassinated by Irish Republican Army (IRA) members earlier that same day. Later that evening, three IRA prisoners were beaten to death by their British jailers, allegedly for trying to escape.

Because of the unusually large number of killings, that date has ever since been known as “Bloody Sunday.”

Since that time, Croke Park has been hallowed ground for Irish Nationalists and the spectacle of a British monarch appearing there would have at one time been unimaginable.

Earlier in the day, the Queen laid a wreath to honor the 50,000 Irish soldiers who perished in World War I at the Irish National War Memorial.