Final answer:
Evacuation Day, celebrated on March 17, 1776, marks the British evacuation of Boston during the American Revolutionary War, enabled by General George Washington's strategic positioning of Fort Ticonderoga's cannons. Therefore, the correct option is E.
Step-by-step explanation:
On March 17, 1776, known as Evacuation Day, the British evacuation of Boston took place. General George Washington utilized cannons from Fort Ticonderoga, positioning them strategically to oversee both British strongholds and the Boston Harbor, making the British position indefensible. Realizing they could not effectively counter-attack, the British chose to withdraw their forces to Halifax, Nova Scotia, putting an end to the nearly year-long siege of Boston.