A free company (sometimes called a great company) was a late medieval army of mercenaries acting independently of any government, and thus "free". They regularly made a living by plunder when they were not employed; in France they were the routiers and écorcheurs who operated outside the highly-structured law of arms. The term "free company" is most applied to those companies of soldiers which formed after the Peace of Brétigny during the Hundred Years' War and were active mainly in France, but it has been applied to other companies, such as the Catalan Grand Company and companies that worked elsewhere, such as in Italy and the Holy Roman Empire.
The free companies, or companies of adventure, have been cited as a factor as strong as plague or famine in the reduction of Siena from a glorious rival of Florence to a second-rate power during the later fourteenth century; Siena spent 291,379 florins between 1342 and 1399 buying off the free companies. The White Company of John Hawkwood, probably the most famous free company, active in Italy in the latter half of the fourteenth century, was the worst offender among those that preyed upon Sienese factions.
- M.H. Keen, The Laws of War in the Late Middle Ages (University of Toronto Press) 1965.
- The free companies headed by condottieri are discussed as a social rather than biographical phenomenon in Michael Mallett, Mercenaries and Their Masters: Warfare in Renaissance Italy 1974.
- William Caferro, Mercenary Companies and the Decline of Siena (Johns Hopkins University Press) 1998.
- Carr, A. D. (1968/9), "Welshmen and the Hundred Years' War", Welsh History Review/Cylchgrawn Hanes Cymru, 4, pp. 21–46.
- Contamine, Philippe (1984) War in the Middle Ages, part I, sect. 4 "Free Companies, Gunpowder and Permanent Armies" The relevant section in the definitive book on medieval warfare.
- Severus, Alexander (1941), "The Fetish of Military Rank", Military Affairs, 5, pp. 171–176.
- Showalter, Dennis E. (1993), "Caste, Skill, and Training: The Evolution of Cohesion in European Armies from the Middle Ages to the Sixteenth Century", Journal of Military History, 57(3), pp. 407–430.
- Rowe, B. J. H. (1932). "John Duke of Bedford and the Norman 'Brigands'." The English Historical Review, 47(188), pp. 583–600.