The Boyne is a river in the Republic of Ireland. A little over 70 miles long, it rises in County Kildare, flows in a north-easterly direction, and enters the Irish Sea immediately after passing through the town of Drogheda.
The river has given its name to the Battle of the Boyne, fought in 1690 on its banks about 3 miles south-west of Drogheda, between the forces of the deposed King James II (of England, VII of Scotland) and those of King William III and his wife, Queen Mary II, who had succeeded to the English throne on James’s deposition in 1688. William’s army, made up not only of English and Scottish soldiers but of soldiers from the Netherlands and Denmark as well as some French Huguenots, numbered 36,000, significantly more than James’s 23,500. It was also better trained and better armed than James’s, many of whose soldiers were recently recruited Irish and Scottish peasants. William’s victory at the Battle of the Boyne signalled the failure of James’s attempt to regain the English throne, though the final defeat did not come until the following year at the Battle of Aughrim (in County Galway, in the west of Ireland).
King William’s victory at the Battle of the Boyne in 1690 is still commemorated today by annual parades, marches, and bonfires in Northern Ireland on 12th July. The parades and marches are organised by members of the Orange Order and originally celebrated James’s final defeat at the Battle of Aughrim, which took place, according to the 'Old Calendar', on 12th July 1691. However, with the passage of time the Battle of the Boyne became the principal focus of the 'Twelfth of July' celebrations, even though that battle took place not on 12th July 1690, but according to the 'Old Calendar' on 1st July, i.e., according to the 'New Calendar' on 11th July: it was felt that in the campaign against James the Battle of the Boyne was more significant than the Battle of Aughrim; and, moreover, at the Boyne King William commanded his army in person but, having returned to England in the meantime, was not present at Aughrim.
See also Derry - Enniskillen - Boyne - Aughrim.