Nicholas and Mary had three children: In 1688 he entered King James's Irish army as captain in the Earl of Limerick's Dragoons.
After the defeat of the Boyne he was moved to Limerick; and being in that city at the time of its surrender, was included in the articles and secured his estates.
In the first Irish Parliament of William III he took the oath of allegiance, but upon declining to subscribe the declaration according to the English Toleration Act 1688, as contrary to his conscience, he was obliged to withdraw with the other Catholic lords.
In February 1703, he joined with many Irish Catholics in an unavailing petition against the infraction of the Treaty of Limerick.
[3] Lord Barnewall died 14 June 1725, and was buried in a beautiful monument at Lusk.