The Tyrrells were the Lords of Fartullagh, a barony in County Westmeath based on the village of Tyrrellspass, and had held this position since the time of Henry II.
[2] He was also foster-brother to Charles O'Connor of Uí Failghe,[2] an Irish rebel known to the Spanish as "Don Carlos".
[7][2] O'Connor is sometimes mistaken for Prince Carlos, heir apparent to King Philip II of Spain.
[citation needed] When the Nine Years' War commenced in 1594, Tyrrell became a commander of the rebel forces in Leinster under Hugh O'Neill, Earl of Tyrone.
In 1597 the Crown forces commenced a new campaign, involving a three-pronged attack on Ulster, aiming to link up in Ballyshannon.
[3] In recognition of his military victories, Súgán Earl James FitzThomas FitzGerald appointed Tyrrell Colonel General of O'Neill's Munster forces.
[2] Captain Richard Tyrrell joined Hugh Roe O'Donnell on his march southwards to Kinsale where a Spanish armada had landed in September.
[2] The English emerged victorious in the battle, and Tyrrell's troops, like the rest of the confederate forces, faced a decisive defeat.