BOYNE, a river of Ireland, which, rising in the Bog of Allen, near Carbery in Co. Kildare, and flowing in a north-easterly direction, passes Trim, Navan and Drogheda, and enters the Irish Sea, 4 m. below the town last named. It is navigable for barges to Navan, 19 m. from its mouth. Much of the scenery on its banks is beautiful, though never grand. About 2 m. west of Drogheda, an obelisk, 150 ft. in height, marks the spot where the forces of William III. gained a celebrated victory over those of James II., on the 1st of July  1690, known as the battle of the Boyne.
 This was the "old style" date, which in the new style (see Calendar) would be July 11th (not 12th, as Lecky says, Hist, of Ireland, iii. p. 427). The 12th of July is annually celebrated by the Orangemen in the north of Ireland as the anniversary, but this is a confusion between the supposed new style for July 1st and the old style date of the battle of Aughrim, July 12th; the intention being to commemorate both.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)