The words mercenary soldier are apt to provoke revulsion in modern readers. Men who fight and kill for personal gain are pariahs, denied the protection of the Geneva Conventions, and liable to be prosecuted as common criminals if captured. Renaissance historians, versed in Machiavelli, are apt to add additional indictments: militarily ineffective and politically dangerous, or as Machiavelli also described them, “disunited, undisciplined, ambitious, and faithless.” Hardly any wonder that soldiers for hire are given little role in the story of military force and state formation in early modern Europe. There is no place for mercenaries in the grand narrative extending from a sixteenth-century gunpowder-driven military revolution, leading to the expansion of armies to unprecedented size in the seventeenth century, and ending in the eighteenth century with the absolutist state and its “monopoly of violence.” Like dinosaurs in popular myth, mercenary soldiers are a doomed species, irrelevant to the grand narrative’s predestined end.

David Parrott, fellow and tutor in early modern history at New College, Oxford, offers in his second major book a wide-ranging and highly perspicacious revision of the grand narrative, centering on the importance of what Fritz Redlich originally labeled the “military enterpriser.” These could be captains, colonels, or admirals who raised companies, regiments, or fleets on their own financial initiative and then contracted with rulers to make war for pay. Albrecht von Wallenstein, the Bohemian generalissimo who at one point commanded a private army of about 100,000, is the most famous exemplar. Parrott’s key point is that such entrepreneurs were central to the history of warfare in early modern Europe precisely because the contractual mechanism gave rulers access to military resources that would otherwise have lain beyond their reach. Those who played the role of military enterpriser were privileged to stand beyond the reach of state taxation in most cases.

What contract armies made possible was the central transformation of the military revolution, the enlargement of armies and the lengthening of campaigns, a process begun in the mid-sixteenth century and reaching its apex in the Thirty Years’ War. Parrott argues that we have been misled by overfocusing on heroic military innovators (Gustavus Adolphus, Maurice of Nassau) and on tactical manuals, which necessarily overemphasize technological novelties. The real engines of transformation are found in the ability to mobilize capital to pay for troops, their munitions, and supplies, which private enterprise did better than the clumsy bureaucracy of the early modern state. It was not beyond the imagination of statesmen to consider direct state involvement in military or naval affairs. In late sixteenth-century Spain there was sustained debate between advocates of administración (direct state control) and asiento (contract) over the provisioning and supply of armed forces, but as the work of I. A. A. Thompson clearly shows, by the 1620s, asiento had won in every instance.

Parrott is fully aware of the difficulties of contracting, its inherent corruption and political favoritism, and of what happened when the system broke down, leaving unpaid or starving troops to vent their fury on helpless civilians. Wallenstein was, of course, assassinated when he came to be regarded as a threat to the house of Habsburg. But, Parrott argues, there is evidence that matters improved as the Thirty Years’ War dragged on, that contract armies became smaller, more efficiently operated, and tactically more effective than in the early decades. Bellum did indeed se ipse alet, war did come to feed itself — evidence, Parrott claims, of the increasing efficacy of contract warfare.

This is an extremely important book. It marks a major reevaluation of almost everything we have believed about warfare in early modern Europe. It is not a picture of technology-driven change (though Parrott is aware of the significance of such innovations as the flintlock musket and ring bayonet), but instead a clear-eyed and unsentimental thesis showing how administrative and economic developments pushed warfare along specific lines. This is not a book for beginners. Close familiarity with both the Italian Wars (1494–1559) and the Thirty Years’ War (1618–48) are virtual preconditions for understanding the argument. The range of Parrott’s scholarship — especially in the German literature — is prodigious; the footnotes alone are worth the price of admission. Military historians will doubtless debate the details for some time to come, but that is the point: all subsequent work in early modern military history will have to take into account the Parrott thesis.