The Ursuline Convent was initially established to be a boarding school for Catholic girls. There, nuns taught students arithmetic, writing, botany, and chemistry, among other things (via American Heritage.) However, the majority of the girls enrolled at the institution were Protestants from upper-class families. With a population of about 50 to 60 students, fewer than 10 were Catholics.

Before the riots, Charlestown received reports of a woman who had attempted to escape the convent after being kept there against her will. Local newspapers ran stories with controversial headlines speculating on the activities happening inside the convent, going as far as saying it was a place of torture and grisly murders. Although some papers retracted their statements, the news has already spread and further ignited the hate that some Protestants had for the Catholics. It also didn’t help that the Ursuline Convent’s Mother Superior, Sister Mary Edmond St. George, was said to be an assertive and arrogant woman, per Mass Moments.

The working-class Protestants took action. They pressured authorities to investigate the convent, and if they didn’t, the Protestant citizens would take matters into their own hands. Messages on placards were posted in the areas of Boston, according to McGill, saying, “It is your duty gentlemen to have this affair investigated immediately. If not the Truckmen of Boston will demolish the Nunnery thursday night — August 14.”