The abbey was at this time governed by Pierre Le Roy, one of its ablest abbots and most famous constructors. He rebuilt the summit of the _Tour des Corbins_ (_merveille_), restored, and re-roofed the abbey buildings to the south of the church, which, begun by Richard Justin in 1260, were carried on at intervals by his successors till they were partially destroyed by the fire of 1374. He completed the eastern defences by the addition of the square tower at O on the plan (Fig. 151), in which he built several rooms for the accommodation of his soldiers. The tower is known as the _Tour Perrine_, in memory of its author. We have seen that the abbots gradually became great feudal chieftains; the Abbot of Mont St. Michel was further commandant of the place for the king; and he was empowered to bestow feofs on the nobles of the province, who bound themselves in return to keep guard over the mount in certain contingencies, enumerated in the following rendering of a Latin text:--[63] [63] Ed. Corroyer, _Description de l'Abbaye du Mont St. Michel et de ses Abords_. "The tenure of these vavassories was by faith and fealty, and their holders were bound to furnish relief and thirteen knights, each of whom was to come in person to guard the gate of the abbey when necessary--that is to say, in time of war; each to keep guard for the space of the ebb and flow of the sea--that is to say, during the rising and falling of the tide; and each to be provided with gambeson, casque, gauntlets, shield, lance, and all requisite arms; and further to present themselves thus armed yearly at the feast of St. Michael in September."