Routiers were mercenary soldiers of the Middle Ages. Their particular distinction from other paid soldiers of the time was that they were organised into bands or routes. The term is first used in the 12th century but is particularly associated with free companies who terrorised the French countryside during the Hundred Years' War.
Although paid soldiers were known before the 12th century, the phenomenon of distinct bands (German Rotten, French routes) of mercenary soldiers, often mainly footsoldiers (spearmen, slingers, javelineers, archers and crossbowmen), appears to date from the mid 12th century. Exactly what distinguishes these mercenaries from simple paid soldiers is disputed by scholars but common elements include fighting for profit (as opposed to other reasons such as fealty or faith) and a "foreignness" of coming from a different geographical area to that in which they were fighting. Numerous different terms were used for these troops, some geographical (e.g. Brabançons from Brabant, Aragones from Aragon, Bascoli from the Basque country) and others nicknames (e.g. cotereaux or cotereli, perhaps from the knife they carried).
Mercenary bands were mainly seen in France, Aquitaine and Occitania but also Normandy, England and the lands of the Holy Roman Emperor. They were noted for their lawlessness, with many complaints from the church about their depredations, leading to an explicit condemnation by the Third Lateran Council in 1179. Mercenary bands continued to be used but by the early 13th century they began to decline. While useful, they became increasingly unpopular. In England, not only was their brutality condemned, but the rise of mercenary leaders of lowly origins to high office caused friction within the nobility. King John's use of mercenaries in his civil wars led to condemnation and banishment of mercenaries in Magna Carta in 1215. Mercenary bands also fell from favour in France in the early 13th century, the end of the Albigensian Crusade and the beginning of a long period of domestic peace removing the context in which the routiers flourished.