[3] The 11-month siege of Boston ended when the Continental Army under the command of George Washington fortified Dorchester Heights in early March 1776 with cannons captured at Ticonderoga.

British General William Howe's garrison and navy were threatened by these positions, and they were forced to decide between attack and retreat.

Howe decided to retreat in order to prevent what could have been a repeat of the Battle of Bunker Hill, withdrawing from Boston to Nova Scotia on March 17, 1776.

[5] A 1941 law established the holiday in Suffolk County, signed in both black and green ink.

The Allied War Veterans of South Boston mark the day with a ceremony on Dorchester Heights.