In 1770 Capt. John Montresor, the highest-ranking British army Engineer in North America, came to Boston to assess its defenses. Those fortifications had been designed over time to prevent an attack by sea, most likely by the French but perhaps by the Spanish.
The main protection was a harbor island called Castle William. It included a big fort, the Royal Battery and Shirley’s Battery along the eastern shore, and a couple more fortified and armed positions. Here’s a modern diagram of the island, based on work by Ens. Henry DeBerniere in 1775.
There were also artillery batteries on other spots in the harbor, such as Governor’s Island, which, Montresor wrote, “anno 1744, was fortified when Duc D’Anville was expected.” That French admiral’s armada actually reached North America in 1746, and its approach to Boston inspired Longfellow’s “Ballad of the French Fleet.”
In addition, Montresor wrote, “There are 3 Batteries—two at Boston and one of Charleston all directed to the water, all in very bad repair. The North Battery the best, though bad, the South Battery the next, and the Charleston one irreparable.” Since the end of the last war, Massachusetts hadn’t seen maintaining those fortifications as a spending priority.
This is Montresor’s count of cannon in and around Boston, as published in his papers by the New-York Historical Society.
For many years, Massachusetts had the responsibility to staff those fortifications through its militia system. But in October 1770, Gov. Thomas Hutchinson announced that as military commander of the province he was removing local troops from Castle William and turning it all over to the British army regiment stationed there since the Boston Massacre. Whig legislators objected, but they couldn’t do anything to reverse that. (After all, they had demanded that Hutchinson send the army regiments out to the island in the first place.)
Then British soldiers returned to Boston in May 1774. The Royal Artillery took over the town’s South Battery to store its supplies. That left the North Battery still in local hands, as well as the Charlestown battery across the river.
As I describe in The Road to Concord, during the first week of September 1774, the people of Charlestown took all the cannon and supplies out of their battery and hauled them inland. Those guns—Montresor had counted five eighteen-pounders—became the start of the Massachusetts Patriots’ secret artillery force.
TOMORROW: A busy night in Boston.