Fusiliers is a name given to various kinds of soldiers; its meaning depends on the historical context. While fusilier is derived from the 17th-century French word fusil – meaning a type of flintlock musket – the term has been used in contrasting ways in different countries and at different times, including soldiers guarding artillery, various elite units, ordinary line infantry and other uses.
Flintlock small arms were first used militarily during the early 17th century. Flintlocks, at the time, were more reliable and safer to use than matchlock muskets, which required a match to be lit near the breech before the weapon could be triggered. By contrast, flintlocks were fired by flint. By the time of the English Civil War (1642–1652), one flintlock musket, the snaphance, was in common use in Britain.
The term fusiliers was first used officially by the French Army in 1670, when four fusiliers were distributed amongst each company of infantry. The following year the Fusiliers du Roi "("King's Fusiliers"), the first regiment composed primarily of soldiers with flintlocks, was formed by Sébastien Le Prestre de Vauban.
Guarding and escorting artillery pieces was the first task assigned to the Fusiliers du Roi: flintlocks were especially useful around field artillery, as they were less likely than matchlocks to accidentally ignite open barrels of gunpowder, required at the time to load cannons. At the time, artillery units also required guards to maintain discipline amongst civilian draymen. Hence the term fusilier became strongly associated with the role of guarding artillery in Britain and the English-speaking world, especially after the formation of the first official "Fusilier" units, during the 1680s.