Cathal Crovderg now obtained the assistance of the Lord Justice, who plundered Clonmacnois. He also purchased the services of FitzAldelm, and thus deprived his adversary of his best support. The English, like the mercenary troops of Switzerland and the Netherlands, appear to have changed sides with equal alacrity, when it suited their convenience; and so as they were well paid, it mattered little to them against whom they turned their arms. In 1201 Cathal Crovderg marched from Limerick to Roscommon, with his new ally and the sons of Donnell O’Brien and Florence MacCarthy. They took up their quarters at Boyle, and occupied themselves in wantonly desecrating the abbey. Meanwhile Cathal Carragh, King of Connaught, had assembled his forces, and came to give them battle. Some skirmishes ensued, in which he was slain, and thus the affair was ended. FitzAldelm, or De Burgo, as he is more generally called now, assisted by O’Flaherty of West Connaught, turned against Cathal when they arrived at Cong to spend the Easter. It would appear that the English were billeted on the Irish throughout the country; and when De Burgo demanded wages for them, the Connacians rushed upon them, and slew six hundred men. For once his rapacity was foiled, and he marched off to Munster with such of his soldiers as had escaped the massacre. Three years after he revenged himself by plundering the whole of Connaught, lay and ecclesiastical.
During this period Ulster was also desolated by civil war. Hugh O’Neill was deposed, and Connor O’Loughlin obtained rule; but the former was restored after a few years.
John de Courcy appears always to have been regarded with jealousy by the English court. His downfall was at hand, A.D. 1204; and to add to its bitterness, his old enemies, the De Lacys, were chosen to be the instruments of his disgrace. It is said that he had given mortal offence to John, by speaking openly of him as a usurper and the murderer of his nephew; but even had he not been guilty of this imprudence, the state he kept, and the large tract of country which he held, was cause enough for his ruin. He had established himself at Downpatrick, and was surrounded in almost regal state by a staff of officers, including his constable, seneschal, and chamberlain; he even coined money in his own name. Complaints of his exactions were carried to the King. The De Lacys accused him of disloyalty. In 1202 the then Viceroy, Hugh de Lacy, attempted to seize him treacherously, at a friendly meeting. He failed to accomplish this base design; but his brother, Walter, succeeded afterwards in a similar attempt, and De Courcy was kept in durance until the devastations which his followers committed in revenge obliged his enemies to release him.