Diarmaid of Armagh was a Catholic Bishop of Armagh. He was made Bishop of Armagh in 834, but was driven from his see by the usurper Foraunan in 835. However, he claimed his rights and collected his cess

Cess

The term cess generally means a tax. It is a term formerly more particularly applied to local taxation, and was the official term used in Ireland when it was part of the United Kingdom of Great Britain and Ireland; otherwise, it has been superseded by "rate"...

 in Connacht

Connacht

Connacht , formerly anglicised as Connaught, is one of the Provinces of Ireland situated in the west of Ireland. In Ancient Ireland, it was one of the fifths ruled by a "king of over-kings" . Following the Norman invasion of Ireland, the ancient kingdoms were shired into a number of counties for...

, in 836. He lived in a stormy age, as the Scandinavian rovers under Turgesius

Turgesius

Turgesius was a Viking chief active in Ireland who is said to have conquered Dublin. It is not at all clear whether the names in the Irish annals represent the Old Norse Thurgestr or Thorgísl...

 seized Armagh

Armagh

Armagh is a large settlement in Northern Ireland, and the county town of County Armagh. It is a site of historical importance for both Celtic paganism and Christianity and is the seat, for both the Roman Catholic Church and the Church of Ireland, of the Archbishop of Armagh...

 in 841 and leveled the churches. The Annals of Ulster

Annals of Ulster

The Annals of Ulster are annals of medieval Ireland. The entries span the years between AD 431 to AD 1540. The entries up to AD 1489 were compiled in the late 15th century by the scribe Ruaidhrí Ó Luinín, under his patron Cathal Óg Mac Maghnusa on the island of Belle Isle on Lough Erne in the...

describe him as one of "the wisest of the doctors of Europe". His feast

Calendar of saints

The calendar of saints is a traditional Christian method of organizing a liturgical year by associating each day with one or more saints and referring to the feast day of said saint...

is celebrated on April 24 .