The O'Sullivan Planxty is a bagpipe tune written to celebrate the epic march of Donal Cam O'Sullivan Beara to O'Rourke's castle in 1602.
The name 'planxty' comes from a word used by the classic harper Turlough O'Carolan in many of his works, and is thought to mean a tribute to a particular person ("Planxty Irwin", for example, being a tribute to Colonel John Irwin of Sligo.) "Planxty" is believed to be a corruption of the irish word and popular toast "sláinte", meaning "good health". Others claim that the word is not Irish in origin but comes from the Latin "plangere," meaning to strike or beat. It is also believed that its origin may stem from the Irish phrase "phlean on ti" meaning "from the house of". During the penal law era of Ireland's history songs sung through Irish were outlawed and it is believed that the use of the phrase Planxty followed by the name of the composer was to disguise the true identity of the composer (it was assumed that Planxty was the first name of the composer) while still giving them credit for the song.
The tune of the O'Sullivan song is based on the O'Sullivan Planxty.