Maurice FitzGerald, 3rd Baron of Offaly, seems to have parted temporarily with his interest in Kilkea to Christiana de Marisco, a niece of his wife’s, through whom a royal claim on the manor was established. In 1317 it appears to have been in possession of the Wogan family. Sir Thomas de Rokeby, Lord Justice of Ireland, died in the castle in 1356.

In 1414, the O’Mores and O’Dempseys, having invaded the pale, Thomas Cranly, Archbishop of Dublin, and Lord Deputy, accompanied the Royal troops as far as Castledermot, where he and his clergy remained praying for the success of the arms. The opposing forces met at Kilkea, where a battle was fought, in which the Irish were defeated. A great many human bones having been found in a field south of the castle, it is likely to have been the scene of this conflict.

John FitzGerald, 6th Earl of Kildare, nicknamed “Shaun Cam,” or Hump-back John, again defeated the native Irish at Kilkea in 1421.

It was here, too, that the “Great Earl,” Gerald FitzGerald, 8th Earl of Kildare and Lord Deputy of Ireland, got his death wound. In August, 1513, he started on an expedition against a castle belonging to the O’Carrolls, and now known as Leap Castle, in the King’s County. While the Earl was watering his horse at the River Greese, near Kilkea, attended by the Mayor of Dublin and a splendid retinue, he received a wound from one of the O’Mores of Leix, which in a few days proved fatal. He was moved by gentle stages to Kildare, where he died. He was thirty-three years Chief Governor of Ireland.

During the rebellion of the “Silken Thomas,” 10th Earl of Kildare, in 1535, Kilkea seems at first to have formed one of the headquarters of his native sympathisers. The surrounding country having, however, been laid waste by the Earl of Ossory, we read that he made an appointment with Sir William Skeffington, the Lord Deputy, to meet him at Kilkea. He waited with his army for three days, but the Lord Deputy being ill, he did not arrive.

In 1537 the King appointed Lord (James) Butler to be Constable of the Castles of Catherlagh (Carlow) and Kilkea. Some years later a Walter Peppard, one of the gentlemen ushers of the King’s chamber, seems to have been in possession of the castle.

The 11th Earl lived largely at Kilkea after the restoration of his title and lands. In 1575, when apprehended on suspicion of treason, one of the charges was that he had interviewed and entertained rebels at Kilkea.

Elizabeth, widow of the 14th Earl of Kildare, was granted the Manors of Kilkea and Graney by the King, as she had no jointure. She was a daughter of Lord Delvin, and had married the Earl by dispensation of the Pope, she being a Roman Catholic. In 1618 she wrote a most touching letter from Kilkea to the Privy Council, beseeching them to allow her the guardianship of her little son Gerald, the 15th Earl—then just over six years old—until he should be older and stronger, urging that he was “the only son of his father.” The infant Earl died some two years later at Maynooth, being succeeded by his cousin George, known as the “Fairy Earl.”

In 1634 the Countess gave Kilkea to the Jesuits, who retained possession of the castle until 1646, in which year the Superior of the Order entertained the Pope’s Nuncio sumptuously at the castle.

During the civil war, which began in 1641, Kilkea was taken and re-taken several times; but on the restoration of peace, both the 16th and 17th Earls seem chiefly to have resided there.