1. The Battle of Breed's Hill: On June 21, 1775, the Battle of Breed's Hill took place in Charlestown, Massachusetts. Though often referred to as the Battle of Bunker Hill, it actually took place on Breed's Hill. The battle was a pivotal moment in the American Revolution, as the colonial forces were able to hold their own against the British army.

2. The Salem Witch Trials: On June 21, 1692, five women were examined for witchcraft in Salem, Massachusetts. This was part of the larger Salem Witch Trials, which resulted in the execution of 20 people and the imprisonment of many others.

3. The first American baseball game: On June 21, 1846, the first documented baseball game in the United States was played in Hoboken, New Jersey. Though the game did not take place in Massachusetts, baseball is a sport that is deeply tied to the state's history and culture.

4. The Dunkirk evacuation: On June 21, 1940, a group of 16,000 British soldiers was evacuated from the French port of Dunkirk during World War II. One of the ships that participated in the evacuation, the RMS Aquitania, was built in Massachusetts.

5. The Boston Tea Party: On June 21, 1774, Bostonians held the first of many town meetings in response to the British Parliament's passage of the Coercive Acts, which were designed to punish the colonies for the Boston Tea Party. The meeting helped to galvanize support for independence and set the stage for the American Revolution.