Where the Armstrong name comes from

Armstrong began as a Middle English nickname for someone with strong arms. In Middle Scots the name was written Armestrang, and it took root in the Anglo-Scottish Borders. One old tradition holds that an early king of Scotland gave it to Fairbairn, his armour-bearer, after a feat of strength in battle. Clan Armstrong grew into a Border Reiver clan, based mostly on the English side of the border. Many of its members received lands in County Fermanagh and neighbouring Irish counties during the Ulster Plantations.

In Ulster the name also served as an English form of two Gaelic names: Mac Thréinfhir, meaning "son of the strong man", and Ó Labhraidh Tréan, meaning "strong O'Lavery". The second of these also survives as Trainor, Traynor and McLavery. By 1969 Armstrong was the 171st most common surname in the United States.