The Battle of Moira is fought between the High King of Ireland and the Kings of Ulster and Dál Riata. It is claimed to be the largest battle in the history of Ireland.

The Battle of Moira, also known as the Battle of Magh Rath, was fought in the summer of 637 by the High King of Ireland, Domnall II, against his foster son Congal Cáech, King of Ulaid, supported by his ally Domnall Brecc, King of Dál Riata. The battle resulted in a decisive victory for the High King and his army, and Congal Cáech was killed in the fighting.

High King of Ireland was a royal title in Gaelic Ireland held by those who had, or who are claimed to have had, lordship over all of Ireland. The title was held by historical kings and was later sometimes assigned anachronously or to legendary figures.

Ulster is one of the four provinces of Ireland, located in the northern part of the island. It is made up of nine counties, with six of these comprising Northern Ireland, while the remaining three are in the Republic of Ireland.

Dál Riata or Dál Riada was a Gaelic kingdom that encompassed the western seaboard of Scotland and north-eastern Ireland, on each side of the North Channel. At its height in the 6th and 7th centuries, it covered what is now Argyll in Scotland and part of County Antrim in Northern Ireland. After a period of expansion, Dál Riata eventually became associated with the Gaelic Kingdom of Alba.

June 24 is the 175th day of the year in the Gregorian calendar; 190 days remain until the end of the year.