St. Patrick's Day is often associated with Boston for good reason. About 1 in 5 of the city's residents claim to have Irish heritage, so March 17 is always a big day for sporting shamrocks, wearing green, and drinking beer.
The partying goes back centuries. Check out this advertisement from 1772 announcing Irish gentlemen gathering at the Green Dragon Tavern to celebrate the day. (Join our tours to drink at the present-day Green Dragon, which is owned by an Irish family.)
But March 17 is also known as Evacuation Day in Boston because it marks that last time that British redcoats occupied the city. During the American Revolution, Boston was under seige for over a year before the general of the new Continental Army, George Washington, broke the stalemate by occupying Dorchester Heights in present-day South Boston. When British General William Howe saw the cannon trained down on Boston, he agreed to leave and not burn the town down, so long as Washington's troops did not fire on them as they departed.
Thousands of soldiers and Loyalists evacuated on March 17, 1776 and that date became appropriately known as Evacuation Day. Today you can visit the monument honoring the site of Washington's cannon. Be sure to look back at the city's skyline and do your best to picture the incredible offensive position Washington's team took. And since you're in Southie, you might as well stop somehwere and get a beer. (We just don't recommend going on March 17, as it is overwhelmingly busy.)
If you want to learn more about Evacuation Day, you can read the book by Ye Olde Tavern Tours's founder, Brooke, entitled Boston in the American Revolution: A Town Versus an Empire.