Mac Coisdealbhaigh was a member of the Costello family of Connacht. His brother was the soldier and poet, Tomás Láidir Mac Coisdealbhaigh. Dudley Costello was an officer in the army of the Confederate Catholics in 1642, and later became a colonel in the Spanish army. Returning to Ireland after the Restoration and disappointed by his failure to recover the family estates, he devoted the rest of his life to wreaking vengeance on the new Dillon proprietors. Proclaimed a tory and a rebelin the summer of 1666, Mac Coisdealbhaigh "carried out a :wikt:vendetta|vendetta of raids and burnings against Viscount Dillon in the baronies of Costello and Gallen, in east Mayo, until he was shot dead by the soldiers of Captain Theobald Dillon in Coolcarney... Bunnyconnellan, early in March 1667.". His head was hung from the St. James Gate in Dublin, today the home of Guinness. He is featured in Dubhaltach Mac Fhirbhisigh's Leabhar na nGenealach at 827.2, as Dubhaltach Caoch, and in his Cuimre as Dubhaltach Colonel, mac Suirtain Buidhe Mec Goisdelbh. A 19th-century namesake and kinsman was Dudley Costello.
Clann Coisdealbhaigh (after Mac Fhirbhisigh)
, fl. 1172. | | William de Angulo, aka William Mac Coisdealbhaigh | | Miles Bregach Mac Coisdealbhaigh | |______________________________________________ | | | | | | Hugo, d. 1266? Gilbert Mor Phillip, fl. 1288. | | | | | |____________________________ Jordan, d. 1324? Gilbert Og, k. 1333. | | | | | | | | Jordan Duff Baldraithe/Baldrin John. John, fl. 1366. | | | Mac Jordan Duff Mac Phillip | Jordan na Bertaighecht | ___________________|_____________ | | | | Edmond an Machaire, k. 1437. William | |_________________________________________________________________________________________________________________ | | | | | | John Duff, d. 1487. William Walter | | | | |_________________________________________ ____________________| Gilleduff | | | | | | | | | | | |_________________ Walter, k. 1545 John Dubh, fl. 1536. Jordan Glegil Hubert John | | | | | | | | | | | | | |___________ Jordan John, k. 1536 Rudhraighe Piers, k. 1555. William Gilladuff | | | | | | | | | | | | | |____________ Thomas Jordan Boy Jordan Buidhe Jordan William David | | | | | | | | | | | | | | | |_______________________ _________| _________|____________ Edmond John Walter David Dubhaltach Edmond | | | | | | | | fl. 1586. | | | | David Richard | | | | John Jordan Buidhe William Caech Edmond William Calvach Jordan Boy, fl. 1585 k. 1589 | _________________________________________________________________________________________________________________________| | | | | | | | | Tomás Láidir Mac Coisdealbhaigh Dubhaltach Caoch Mac Coisdealbhaigh Edmond Dubh Calbhach Ban fl. 1660s. killed 3 March 1667.
