In May, 1655, Vauban received his commission as engineer, and in the following year he was rewarded for his services with the command of a company in the regiment of the Maréchal de la Ferté. Not to mention the numerous situations in which he bore an active but subordinate part, we proceed at once to the year 1658, in which he had the chief direction of the sieges of Gravelines, Ypres, and Oudenarde; where, being free to act on his own opinions, yet still doubting his strength, he showed, by judicious though slight innovations, what might be ultimately expected from his matured experience. He was also charged with the improvement of the port and fortifications of Dunkerque, on the surrender of that once important place to France by the treaty of October 17, 1662. When the war with Spain was renewed in 1667, Vauban had the principal direction of the sieges at which Louis XIV. presided in person. At Douay he received a musket-wound in his cheek, the scar of which is preserved by Coisevox and Lebrun in his bust and portraits. The capture of Lille, after only nine days of open trenches, procured for him a lieutenancy in the Guards and a pension, accompanied with the far more gratifying commendations of his sovereign. Hostilities were ended by the treaty of Aix-la-Chapelle, in 1668, in which year he prepared designs for the citadel of Lille, for Ath, and several other places; and in 1669 the king appointed him governor of the citadel of Lille, the first reward of this description created in France. Soon after the peace Vauban accompanied the minister Louvois on a mission to the Duke of Savoy, and furnished plans for the fortifications of Verrue, Verceil, and the citadel of Turin. Returning to Flanders, the works of Dunkerque were prosecuted under his immediate direction with unexampled activity. Three corps of 10,000 men relieved each other daily, every four hours, proceeding from the camp with their arms, and resuming them on the completion of their task. In the midst of these labours he prepared his first work on the attack of fortresses, for the instruction of Louvois, pointing out in it many of the errors committed in former sieges, and proposing remedies for them.