During the late Middle Ages, Mercenary forces grew in importance in Europe, as veterans from the Hundred Years' War preffered to continue living a soldier's life rather than abandoning the military. Swiss soldiers in particular were valued for their loyalty and skills, and several European countries - mainly the Netherlands and France - had Swiss Pikemen regiments into their armed forces under treaties with the various Swiss cantons.

Since 1859 however, only one mercenary unit is permitted under Swiss law, certainly the most famous of all: the Vatican's Swiss Guard, which has been protecting the Pope for the last five centuries.