On the outbreak of Tyrone's rebellion the extreme severity with which his country was treated by Tyrone on his march into Munster, early in 1600 induced Delvin to submit to him; and, though he does not appear to have rendered him any active service, he was shortly afterwards arrested on suspicion of treason by the current Lord Deputy, Mountjoy, and imprisoned again in Dublin Castle. He died in the castle before his trial, apparently on 17 August 1602, though by another account on 5 September or 1 October, and was buried at Castle Delvin on 5 October. Delvin married Lady Mary FitzGerald, daughter of Gerald FitzGerald, 11th Earl of Kildare, and Mabel Browne; she died 1 October 1610. His and Mary's children were:   Delvin was the author of:  1. "A Primer of the Irish Language, compiled at the request and for the use of Queen Elizabeth." It is described by John Thomas Gilbert as a 'small and elegantly written volume,' consisting of 'an address to the queen in English, an introductory statement in Latin, followed by the Irish alphabet, the vowels, consonants, and diphthongs, with words and phrases in Irish, Latin, and English.' "A Plot for the Reformation of Ireland", which, though short, is not without interest, as expressing the views of what may be described as the moderate or constitutional party in Ireland as distinct from officialdom on the one hand, and the Irish on the other. He writes that the viceroy's authority is too absolute; that the institution of presidents of provinces is unnecessary; that justice is not administered impartially; that the people are plundered by a beggarly soldiery, who find it to their interest to create dissensions; that the prince's word is pledged recklessly and broken shamelessly, and, above all, that there is no means of education such as is furnished by a university provided for the gentry, "in myne opynion one of the cheifest causes of mischeif in the realme." This incorporates the article by Robert Dunlop in the old DNB, who used the following sources:   Also see: