On June 2 an impressive British fleet of more than 150 vessels, transporting 27,000 men, 13,000 of whom were professional soldiers, arrived off the coast of Louisbourg. In spite of the French reinforcements, the forces of Governor Augustin de Boschenry de Drucour amounted to only a quarter those of the attackers, even taking seamen and militiamen into account. The French garrison knew that it had lost but was determined to hold on to the very end. The British disembarked on June 8, and quickly dug trenches and surrounded the fortress with their artillery, beginning on June 19 to methodically shell the city. The defenders resolutely returned fire. The wife of the governor herself willingly went up onto the ramparts every day to fire three cannon shots, an act that greatly encouraged the garrison and earned her the admiration of the enemy. 
After five weeks of intensive shelling the fortifications were breached in many places, and the artillery was virtually reduced to silence, with the few French warships anchored in the port sunk or burned; the city was reduced to ruins, the civilian population hiding in shelters. On July 26 Governor Drucour inquired about the conditions for surrender. The British refused to grant the honours of war to the French troops, in spite of the bravery they had shown. The French were therefore forced to turn over their arms and their flags. Outraged, most of the officers wanted to continue the battle. The administrative commissioner, Jacques Prévost de La Croix, argued in favour of safety for the civilians, holding that a general assault could degenerate into theft, murder and rape. These arguments were convincing and the surrender was signed that very day.
When the news was announced, the soldiers in the Régiment de Cambis broke their muskets and burned their flags so that they would not have to surrender them, but the other corps met the terms of surrender. 
The garrison was sent to Europe and the entire French population of Île Royale and Île Saint-Jean were deported in the autumn. The fall of the "sentinel of the Gulf of St. Lawrence" opened the way to the capital of New France. But the long and valiant defence by the garrison of Louisbourg required that the British delay their siege of Quebec until the following year.