From a couple of sources:

Deevey
Well known, on account of the famous Fenian John Devoy (1842-1928); the O'Devoys (the anglicized version) or O'Deevys were one of the Seven Septs of Leix, the chief men of which were transplanted to Co. Kerry in 1607. The name has always been associated with Leix and adjoining midland counties. The Gaelic form of the name is Ó Duibh which became the well known Leix name Deevy or Devoy. This is supported by an entry in the Annals of the Four Masters (1071) where the lord of Creamhthainn (i.e. Maryborough) is called Ó Duibh:

"Under Dun Mase of smooth land,
O'Duibh (O'Deevy) is over Cinel Criomthainn,
Lord of the territory which is under fruit,
Land of smoothest mast fruit."

Seven Septs of Laois
After the arrival of the Anglo-Normans, the Leix (Laois) County was divided among seven Septs or Clans: O'Moore, O'Kelly, O'Deevy, O'Doran, O'Lalor, O'Dowling and McEvoy.
This confederation began after the 3rd century CE, when the family group that would become the O'Mores came from Ulster to Leinster under the leadership of Laoighseach Cean More, son of Connall Cearnach of the Red Branch, and helped to defend Leinster under the kingship of Cuchorb, and expelled the Munster forces from the region. They continued to hold principality over what became Leix (Laois), so named after Laoighseach, and this confederation continued through the Elizabethian wars of the 1500's, when the military and political power of the families were broken and the clans dispossessed and relocated...


It was the incident at Mullaghmast in 1577 that really broke the power of the Seven Septs when most of the leaders were massacred by ambush at what was supposed to be a peaceful meeting. But the attackers were unsuccessful in their main objective, since Rory Og O'More, the then-leader of the Seven Septs wasn't there and he rallied many more to his cause afterwards with the battle-cry "Remember Mullaghmast!" They practiced a pretty brutal form of guerilla warfare on the transplanted English and their Irish allies from the massacre for years (in point of fact, Rory Og had been doing this before the massacre and that was the main cause of it in the first place), until O'More was betrayed, escaped with much loss including his family, and later died in an unsuccessful rally. The pinnacle of revenge for Mullaghmast was probably achieved with the events inspiring the song Follow Me Up to Carlow, though Rory Og didn't live to see it.


Anyway, big fuzzy deal... except to say that that's why, though I heartily dislike jingoistic rebel songs and refuse to do them, I still perform "Follow Me Up to Carlow" regularly. Besides, it can really kick ass the way we do it.   ;)