Lorcan Ua Tuathail, or Lawrence O'Toole, was born around 1128 near Castledermot, County Kildare, Ireland, of a marriage between the Irish chieftain families of O'Toole and O'Bryne.
When only ten years old, he was taken hostage by the raiding King Dermot McMurrogh of Leinster, who treated the child inhumanely. After two years, his father obliged the tyrant to place Lawrence in the care of the Bishop of Glendalough.

In 1153, after a period of serving as a monk of the monastery at Glendalough, he was chosen abbot on the death of the bishop. He was but twenty-five years of age, but he governed his large community with wonderful virtue and prudence.
In 1161, Lawrence was consecrated the Archbishop of Dublin. He initiated reforms among the clergy, upgraded the caliber of new clerics and imposed strict discipline on his priests.
At the second siege of Dublin in 1170, Lawrence was active in ministration, trying to negotiate accords with the Irish chieftains and King Henry II of England. Henry himself went to Ireland in 1171, received the submission of most of the Irish chieftains, and the beginning of the “troubles” between Ireland and England began.

In 1175, Lawrence went to England to negotiate a treaty between Henry and Rory O’Connor, and was attacked while visiting the Shrine of Thomas Becket. While advancing to the altar to say Mass, a maniac, who had heard very much of his sanctity, struck him a violent blow to the head. All present thought he was mortally wounded. But the saint coming to himself asked for some water, blessed it and had his wound washed with it. The flow of blood was immediately stopped and he celebrated Mass.

After attending the Lateran Council in 1179, Lawrence was named Papal Legate to Ireland.
Our Saint ended his journey here on earth on the 14th of November 1180, and is buried in the church of the Abbey at Eu, on the confines of Normandy, near Rouen, France.
He was canonized in 1225 by Pope Honorius III. His feast is celebrated November 14th.