Wicklow is situated about twenty-five miles south-south-east of Dublin, and the ruins of the Black Castle occupy an isolated rocky promontory east of the town, and on the south side of the Leitrim river. The name Wicklow is likely to have been of Norwegian origin, but the meaning is uncertain. The Irish name Kilmantan signified S. Mantan’s Church. The castle followed the natural shape of the dark rock on which it was built, and from which, no doubt, the designation “Black” is taken. It was divided from the mainland by a chasm, which was probably bridged in former times. A few fragments of walls, with window openings, are all that remain.

The fortress can never have been of large dimensions if it was confined to the rock on which the ruins now stand.

In 1176, after Maurice FitzGerald had been recalled by Strongbow, he received a grant of the Castle of Wicklow, among other possessions, in lieu of his lands in Wexford, which King Henry wished to retain. From this it would appear to have been the site of an older fortification.

Maurice FitzGerald began to erect a Norman stronghold on the promontory, but he died before it was completed.

Soon after his death William FitzAdelm managed by falsehood to get possession of the Black Castle from his son Gerald, first Baron of Offaly, and surrendered him instead the unprotected Castle of Ferns.

The Earl of Ormond being arraigned for treason in 1422, one of the charges against him was that he had retained William Edward, Constable of Arklow, in his service after he had assisted the O’Byrnes in seizing the King’s Castle of Wicklow. They killed John Liverpoole, the constable, and sent his head to the O’Byrne. They also imprisoned a priest, whom they found in the fortress, to hold for ransom.

The O’Byrnes seem to have been in possession of the castle in the early part of the sixteenth century, but in 1534 it had again passed to the Crown, and Thomas Stevyns was appointed constable. In 1567 Sir Thomas Fytzwylliams began his suit for the fortress, which, in 1575, he offered to re-edify, though his doing so does not seem altogether to have worked in his favour.

It seems generally believed that the present ruins represent the stronghold he built, but in 1580 it was reported that Wicklow Castle was razed by the enemy.

Nineteen years later the terrible disaster took place in June, 1599, in which the English troops were utterly routed between Rathdrum and Glenmalure by the combined Irish septs of the district. It was this that caused Essex such a sharp reprimand from Oueen Elizabeth.

Sir Henry Harrington was in command, and his troops fell back upon Wicklow Castle in the wildest disorder, chased by the Irish within half a mile of the town.

Captain Adam Loftus seems to have been the only one who endeavoured to redeem the day. He was wounded in the leg and conveyed to the castle. A surgeon was sent for, though the wound was not considered dangerous at first; but he shortly afterwards succumbed to the effects.

In 1610 Sir William Usher, Knight, was made constable of the fortress, and in 1641 Luke O’Toole and a band of insurgents laid siege to the town and castle, but retreated upon the approach of Sir Charles Coote with some English troops.