Swiss mercenaries (
Reisläufer) were notable for their service in foreign armies, especially the armies of the Kings of
France, throughout the
Early Modern period of European history, from the
Later Middle Ages into the Age of the
European Enlightenment. Their service as
mercenaries was at its peak during the
Renaissance, when their proven battlefield capabilities made them sought-after mercenary troops. There followed a period of decline, as technological and organizational advances counteracted the Swiss' advantages.
Switzerland's military isolationism largely put an end to organized mercenary activity; the principal remnant of the practice is the
Swiss Guard at the Vatican.