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O'Cannon (MacCannon)
Cannon is a common English surname derived from the ecclesiastical word canon. It is also the anglicized form of the name of two quite distinct Irish septs. Though identical in English these two are different in Irish. On is O Canain: this is a Hy many (Ui Maine) sept of the same stock as the O'Maddens and belongs to southern Co. Galway though nearly extinct there now. The other is O Canannain abbreviated to O Canann, an old Tirconnell sept, whose chiefs the annalists call Kings of Cinel Conaill: it was subjugated by the powerful O'Donnells in the thirteenth century and sank into obscurity. Descendants of Minor families of the sept, however, remained in their ancestral territory: in the seventeenth century they were numerous in Co. Donegal; priests called Cannon appear from time to time in the records of the diocese of Raphoe; and to-day they are still more numerous in Co. Donegal than anywhere else in Ireland.
The name MacCannon is found in Dublin at the present time and in the records of the city at least as far back as 1744; in the 1659 census it is recorded as numerous in Meath and in 1687 one of the name was Sheriff of Co. Monaghan.
A further point in connexion with the name in Ireland is that several families called Cannon are the descendants of French Protestant refugees. Joseph Gurney Cannon (1836-1926), Speaker of Congress (U.S.A.), for example, was the grandson of an Irishman of Hugenot stock, as also was Charles James Cannon (1800-1860), well known in New York in his day as an author. Another writer of some distinction was the Franciscan friar Rev Francis Cannon (d. 1850), a native of Co. Donegal.
The site of the ancient castle of the O'Cannons was near Letterkenny which is said on good authority to denote the hillside of the O'Cannons, Kenny being used in that district as a synonym of Cannon.
It should be added that Cannon is not used as an abbreviated form of the well-known Connacht name Concannon.