The stronghold was erected in 1564 by Christopher, the twentieth baron, but whether it was built on the site of an older castle or whether Corr Castle, also situated on the peninsular, was the ancient fortress of the St. Laurence family, does not seem to be known.
The mortar of the early building, like the Tower of London, is reported to have been mixed with blood. Until far into the nineteenth century the castle was surrounded by a fosse.
There are several inscribed and figured stones over the entrance to the stable-yard, and also one built into the wall near the garden gate.
Sir John de Courcy and his sister’s husband, Sir Amoricus Tristram, arrived at Howth in 1177. Their companionship in arms is said to have been the outcome of a compact to share each other’s fortunes made in the Church of St. Mary at Rouen.
Upon the arrival of the ship at Howth, De Courcy, being ill, remained on board, while Sir Amoricus took command of their forces in the first engagement with the Danes, who fiercely opposed their landing.
After a great battle, in which Sir Amoricus lost seven blood relations, the enemy were completely defeated at the bridge of the Evora, and the lands of Howth were granted to the victor as a reward of prowess.
He then accompanied Sir John de Courcy to Down, where he also gained possessions and did great deeds of valour. A story is told that after the first battle in the north Sir Amoricus was found leaning on his shield under a hedge, bleeding from three large wounds, and having sustained himself by eating the wild roses and honeysuckle which grew within his reach. His life was despaired of for nine days, but he eventually recovered, and lived to die heroically among a group of outnumbered infantry, having slain his horse so that he could not save himself by flight.
The St. Laurence coat of arms is a shield with cross swords and roses in a bloody field, which may have originated from the wild flowers Sir Amoricus gathered.
An early chronicler says of him that he might “be chosen from amongst a thousand knights for beauty and heroic courage, as well as for humility and courtesy to his inferiors, yielding to none but in the way of gentleness.”
After his death his sons gradually lost his northern possessions, and King John confirmed the grant of the lands of Howth to the third baron by charter. It may have been at this time that the family name was changed from Tristram to St. Laurence. There seems to be no historical evidence for the tradition that the name was altered to commemorate a victory gained upon St. Laurence’s Day.