In Assassin's Creed III, which historical event begins Connor Kenway's main story in Boston?

In Assassin's Creed III, Connor Kenway's main story begins around the Boston Massacre.

The Boston Massacre took place on March 5, 1770, when British soldiers fired on a crowd in Boston, killing five colonists. In the game, the event is presented through the historical-fiction storyline that introduces the colonial conflict and places Connor within the growing struggle between Assassins and Templars.

Connor, whose Mohawk name is Ratonhnhaké:ton, later works with the Assassin Achilles Davenport and becomes involved in the American Revolution. His story spans several decades of colonial and revolutionary history.

The Boston Tea Party and Declaration of Independence also feature in the game or its broader historical setting, but neither is the opening event asked about here. The game uses real events while adapting them to its fictional plot.