In 1759, the Québec fortifications developed by Chaussegros de Léry since 1745 formed a triangle. The first two sides, the St. Charles River and the St. Lawrence River, were protected by the steep cliff that proved to be a natural defence. To increase its effectiveness, a parapet was built, which was broken in two places by the "Côte de la Montagne" and the "Côte du Palais." The third side, extending from Cap Diamant to the St. Charles River, opened on the Plains. A huge wall, 25 to 30 ft high, with six bastions – Joubert, de la Glacière, Saint-Louis, Saint-Ursule, Saint-Jean and de la Potasse – was built. Finally, behind these two last bastions were the Dauphine and du Bourreau redoubts. There were two openings for the wall to pass through: the "porte Saint-Jean" and the "porte Saint-Louis"82.
According to Bougainville and Montcalm, the town was far from being well-fortified, and would be "taken as soon as it was attacked." So, to improve its defences, several temporary works were set up, such as the stockade, designed to completely close the upper town at the top of the cliff, and the re-armament of batteries in the upper and lower town – Château, Clergé, Hôpital, the rampart embrasures (facing the Plains), de la Reine, Royale and Dauphine –, in addition to the new batteries built at the "Quai du Roi", "Pointe à Carcy", "du Palais building site", and on the wharfs belonging to various individuals83.
In order to carry through Québec's defence, Montcalm studied Phips' experience in 1690 and gathered the notices of an engineer, Pontleroy, and the thoughts of his aide-de-camp, Louis-Antoine de Bougainville. In the end, Montcalm agreed to establish a fortified camp and position most of his troops at Beauport between the St. Charles and Montmorency rivers. A second defensive line was located along the east bank of the St. Charles River. The west bank of the river also comprised a defence work designed to block its access. Finally, Montcalm had another battery built, the Samos battery, above Anse-au-Foulon84.