In the early years of the fifteenth century he built the gate-house and crenellated curtain which connects it with the _Merveille_, to the north of the guard-room, _Bellechaise_ (see Fig. 163, beginning of this chapter). The gate-house was placed in front of the northern façade of _Bellechaise_ (D, Fig. 150); an open space between this and the south wall of the new structure formed a wide _machicoulis_ for the protection of the north gate (that of _Bellechaise_), which, by the erection of the new building, had been transformed into a second interior entrance. The gate-house or _châtelet_ is a square structure, flanked at the angles of the north front by two turrets, corbelled out upon buttresses. In general appearance they resemble a pair of huge mortars standing on their breeches. Between the pedestals of these turrets was the doorway and the inclined vault over the staircase leading to the guard-room. This entrance was defended by a portcullis worked from within on the first story, and by three _machicoulis_ at the top of the curtain, between the battlements of the turrets. For the further protection of the gate-house Pierre Le Roy built the barbican which covers it to the east and north, and also commands the great staircase (_Grand Degré_) on the north. He modified the ramparts by the addition of the tower known as the _Tour Claudine_ at the north-east angle of the _Merveille_. In the lower story of this tower he constructed a guard-room, the postern of which communicated with the _Grand Degré_, and by a series of ingenious and unique combinations was so contrived as to command all the approaches.[64] [64] Ed. Corroyer, _Description de l'Abbaye du Mont St. Michel_, etc.; Paris, 1877. [Illustration: 172. MONT ST. MICHEL. SOUTH FRONT (AS IT WAS IN 1875)] In 1411 the Abbot Robert Jolivet was nominated lord of the abbey by Pope John XXIII. After his election by the monks he was made captain of the garrison by the king, but continued to live in Paris. In 1416, however, he hastened to his abbey, which was threatened by the English, who had possessed themselves of Lower Normandy after the battle of Agincourt in 1415. Whilst the English were busy fortifying Tombelaine, Robert Jolivet completed his walls and certain towers round about the town, which still exist. To meet the expenses of his undertaking the abbot obtained a grant from the king of fifteen hundred _livres_ from the revenues of the Viscounty of Avranches, besides a subsidy from the Master of the Mint at St. Lô. [Illustration: 173. MONT ST. MICHEL. FORTIFICATIONS OF THE FOURTEENTH CENTURY (AS RESTORED BY ED. CORROYER)]