In 1565
Gerald FitzGerald, 14th Earl of Desmond, was defeated by the
Butlers in the private
Battle of Affane. In 1567 the 14th Earl and his brother, John of Desmond, were detained and sent to the
Tower of London. During their absence, fitz Maurice became captain general of
County Desmond with the warrant of the Earl. This meant he had authority over the soldiers retained in the service of the Desmond FitzGeralds. This was arranged by
Eleanor Butler, Countess of Desmond who had arrested fitz Maurice. In July 1568, fitz Maurice entered Clanmaurice, the territory of
Thomas Fitzmaurice, 16th Baron Kerry and lord of
Lixnaw, to levy tribute and assert the Desmond overlordship. Having seized 200 head of cattle and wasted the country, he was confronted by Lixnaw himself on the way home and utterly defeated. At the end of 1568, the absent Earl of Desmond granted Sir
Warham St Leger a lease of the barony of Kerricurrihy, which cast fitz Maurice's inheritance into confusion. In 1569 the lord deputy of Ireland, Sir
Henry Sidney, was informed by fitz Maurice that he had assembled the people of Desmond to tell them that the lord deputy was unable to procure the release of the captive earl, who would be executed or perpetually imprisoned, and that the people should proclaim a new earl or captain: with one voice, the people were said to have cried out for fitz Maurice to be captain. The earl's wife, Eleanor Butler, wrote to her husband in November that fitz Maurice was seeking to bring the earl into further disrepute and to usurp his inheritance, "by the example of his father". To reassert Geraldine authority, fitz Maurice then launched what would become known as the first of the
Desmond Rebellions. Southern Ireland erupted into a general rebellion, owing in part to attempts at establishing
plantations. In June 1569, fitz Maurice and the Earl of Clancarty (
MacCarthy Mor) invaded
Kerrycurrihy, spoiled the inhabitants, took the castle-abbey of
Tracton, hanged the garrison, and refused to depart without the surrender to them of the custody of Lady St Leger and Lady Grenville, the wives of the principal English colonists. Fitz Maurice then joined in league with the turbulent brothers of the earl of Ormond, and entered a bond with
Conor O'Brien, 3rd Earl of Thomond, and John Burke, son of the Earl of Clanricard. He wrote to the mayor and corporation of Cork in July ordering the abolition of the new heresy of Protestantism, at a time when he appears to have been taking instruction from Irish Jesuits. By September 1569, Sidney had broken the back of the rebellion and left Sir
Humphrey Gilbert behind to suppress fitz Maurice, who sought refuge in the woods of
Aherlow, south of Tipperary. After Gilbert's departure fitz Maurice raised a new force in February 1570 and by a surprise night attack on 2 March, took
Kilmallock and after hanging the chief townsmen at the market cross, plundered its wealth and burned the town. In February 1571, Sir
John Perrot landed at Waterford as
President of Munster and challenged fitz Maurice to a duel, which fitz Maurice declined with the remark, "For if I should kill Sir John Perrot the Queen of England can send another president into this province; but if he do kill me there is none other to succeed me or to command as I do." Fitz Maurice attacked Perrot, but retreated on mistaking a small cavalry company for the advance party of a larger force. After a second and successful siege by Perrot of the Geraldine stronghold of
Castlemaine, fitz Maurice sued for pardon, which was granted in February 1573, after he prostrated himself in Kilmallock church with the president's sword point next to his heart. Fitz Maurice swore fealty to the crown, and gave up his son as hostage. == Continental intrigue ==