By David Keough, U.S. Army Military History Institute.March 3, 2008
If you play word association with Aca,!A"March 17Aca,!A? and Aca,!A"Boston,Aca,!A? most Americans would say: Aca,!A"Saint PatrickAca,!a,,cs DayAca,!A? or maybe Aca,!A"Saint PatrickAca,!a,,cs Day Parade in South Boston.Aca,!A? There is, however, another holiday associated with that day and city -- Evacuation Day.
After the clashes at Lexington and Concord in April of 1775, the British troops fell back to the city of Boston, and Massachusetts minutemen and other militia took positions outside the city. As more volunteers arrived from other parts of New England, the rudiments of an army took shape in a siege of the British garrison in Boston. In accord with orders from the Continental Congress, George Washington assumed command of the force on June 15, 1775, and slowly created more order among the militia and volunteers.
The siege dragged on into the winter months. The British, backed by the ships of the Royal Navy, seemed content to stay in the city and wait out the men of the new Continental Army and the state contingents. Events took a more serious turn early in 1776. Henry Knox, an artillery officer of the prewar Massachusetts militia, supervised transporting captured cannon from Fort Ticonderoga by sledges over the snow to Boston. Backed by numerous cannon, Washington could now conduct a more active siege of the city.
In a carefully planned operation, American troops seized the hill tops of Dorchester Heights and Nooks Hill south of the city on March 5 and hauled guns to siege works constructed on the hills. From these closer points of high ground, the American guns could now command the neck of land connecting the main area of the city to the broader plains to the south and west. The artillery also threatened to deny the Royal Navy its safe anchorage in Boston Harbor.
After some negotiations, it was agreed that the British would be allowed to evacuate the city, unmolested; they, in turn, agreed not to set the city on fire. On March 17, the British formally completed the evacuation and the Americans took charge of Boston. WashingtonAca,!a,,cs General Order of the Day, officially announcing these events, began as usual with the Parole and Countersign of the day for the guards -- Parole: Aca,!A"BostonAca,!A?; Countersign: Aca,!A"St. Patrick.Aca,!A?
In 1901, the cities of Boston, Cambridge, and Somerville, Massachusetts, made Evacuation Day a local holiday.