A study of French military engineers at a crucial point in the evolution of modern engineering. The origins of the modern science of engineering can be traced to France's Royal Corps of Engineering in the eighteenth century. In Conserving the Enlightenment, Janis Langins gives us a history of this prototypical technical bureaucracy, using as his point of entry a pivotal dispute on the respective merits of two methods of engineering military fortifications. The story he tells of the tribulations of military engineers at the end of the Old Regime sheds light not only on the evolution of modern engineering but also on the difficulty of innovation in a technical bureaucracy. From the days of Louis XIV and his great military engineer Vauban, engineers in France had a reputation for competence and intellectual superiority. (This respect for engineers survived the Revolution; two engineers sat on the new Republic's ruling Committee of Public Safety with Robespierre.) Langins argues that French engineers saw themselves as men of the Enlightenment, with a steadfast faith in science and its positive effects on society; they believed that their profession could improve and civilize even warfare. When Marc-Rene, marquis de Montalembert, a cavalry officer and an amateur engineer, challenged the prevailing wisdom with a new method of fortification, the subsequent factional struggle became a crucible of self-definition for the profession. In the end, Langins shows, Vauban's science won out over Montalembert's inspiration, reinforcing and predicting the essentially conservative nature of French engineering.