Most of the world knows of March 17 as being "St. Patrick's Day," celebrated as a day when people of all nations are Irish For A Day, and people of all faiths commemorate a Christian myth of driving the snakes from Ireland.
However, in the city of Boston, Massachusetts it's also known as Evacuation Day, and is an actual recognized (and take-the-day-off) holiday. (This is a separate holiday from the Evacuation Day formerly celebrated in New York City)
In March of 1776 George Washington's troops, participating in what is now termed "The Siege of Boston," were already in strategic places around the exterior of the City of Boston, and brought in cannon captured by troops under the command of General Benedict Arnold, from Fort Ticonderoga in New York, and transported overland to Boston by General Henry Knox.
Under cover of night, and a light fog, the cannon, and pre-fabricated defensive works, were emplaced on two hills known as Dorchester Heights, on the peninsula of Dorchester Neck. These hills had a commanding vantage over much of the city of Boston, and of Boston Harbor.
After dawn, the commander of the British forces, General Howe, seeing the overnight appearance of the fortifications, attempted an assault, but the March weather conspired to blunt the attempt. Howe, bowing to military reality, agreed to leave the city by sea. When the weather lifted on March 17 Howe, with his troops and loyalist citizens who wished to leave, sailed from Boston Harbor for Halifax.
Since that time, one of the two hills on Dorchester heights has been leveled to provide building materials for the city's expansion in the 1800s. The remaining hill now has a monument tower commemorating the event. (Howe's departure, not the missing hill's)
A few years ago I took a visitor from New Zealand around some of the "sights" in Boston.
The night before her plane was to leave (scheduled for about 3 AM) we did a last round to some of the sights that we had missed, or that were too crowded to appreciate.
One of the locations we had missed was Dorchester Heights, which still retains a magnificent vantage east over Boston Harbor's Dorchester Bay (much of the old harbor that was overlooked from Dorchester Neck to the west has been filled in for the above mentioned expansion). In the evening, with few people about, and more light from a full moon than city lights, it was easy to imagine the vista that Washington and Knox surveyed.
And, yes, she did make her flight on time.