[3] Captured by Jacobite forces, he was released when the war ended with the October 1691 Treaty of Limerick and in 1695, he enrolled in his relative Philip Armstrong's troop, part of Wood's Regiment of Horse, later 3rd Dragoon Guards.

At the start of the War of the Spanish Succession, he served at Cadiz under Ormonde, who recommended him to Holcroft Blood (1660–1707), Marlborough's chief engineer.

'[5] For decades before and after, Dunkirk was a major privateer base for raiding British merchantmen, since it was possible to reach the North Sea in a single tide and escape Royal Navy patrols in the Channel.

[8] In May, Armstrong was at The Foundery in Moorfields watching a demonstration of captured French cannon being recast when an explosion killed 17 of the 25 people present; he was one of the very few to escape injury and the accident led to the institution of the Royal Arsenal in Woolwich.

[9] He returned to England in 1718 with Lascelles taking over at Dunkirk; in addition to his official duties, he was involved in multiple activities, becoming a Fellow of the Royal Society in May 1723.