Among the most dramatic problems faced on the Italian peninsula in the fourteenth century were the raids of marauding mercenary companies. These companies, known locally as Companies of Adventure and more generally as "free companies," were private armies, composed of professional soldiers and adventurers from throughout Europe. They sold their services to the highest bidder in times of war and staged ruinous raids in times of peace.

The city of Siena, visually opulent and wedged between Florence and the lands of the pope - two frequent employers of mercenaries - was a particular target.

In this volume, William Caferro explores the social, economic, and administrative impact of the companies on Siena from the arrival of Werner of Urslingen and the Great Company in 1342 until the fall of the Sienese republic in 1399. During this time, Caferro explains, Siena endured some thirty-seven raids, characterized by arson, pillage, and looting in the countryside and extortion of enormous bribes from the city government.

He shows that the raids constituted a persistent and significant drain on both the human and financial resources of Siena.