The Boston Harbor Islands are a National Recreation Area. George's Island is 40 acres in size, and about 45 minutes from the city via shuttle boat. It's a great place to picnic, fly kites, or explore. The harbor can be subject to hostile weather, and it is advised to plan accordingly when visiting the islands (summer only, with gear). If you will be in Boston for a period of time, and want to escape the city center to a relatively isolated retreat, Georges Island is good choice for a day trip. The island has great history, like so many other places in Boston.
An earthen fortification was constructed on George's Island in 1778. It was built to protect Count d'Estang's French fleet that was under repair in the harbor. British cruisers patrolled the bay and there was great concern they would attack the fleet or even the town. The current Fort Warren was completed in 1850. During the Civil War, the fort was armed with many cannon. Its mission was to protect the harbor, and was also used as a prison for Confederate soldiers and those deemed disloyal to the Union.
The Confederate diplomats of The Trent Affair were imprisoned in Fort Warren at George's Island. The Confederate States had appointed James Mason as minister to England, and John Slidell as minister to France. The pair ran the Union naval blockade, and at Cuba boarded the British merchant ship Trent. On November 8, 1861 the U.S. Navy ship San Jacinto halted and boarded Trent, and arrested the diplomats. They were imprisoned at Fort Warren on November 23, 1861 and released on January 1, 1862. Boarding of the Trent occurred without official sanction and was a violation of international law. The incident could have led to Britain declaring war on the United States.
John Brown's Body, a patriotic song that took the melody from the hymn Oh Brothers Will You Meet Us?, was composed in 1861 at Fort Warren. The glee club of the Massachusetts 2nd Infantry Battalion wrote the song. The Mass 12th Regiment sang it in processions at Boston, New York City, and Baltimore, and the tune quickly spread throughout the ranks of the Army of the Potomac. Julia Ward Howe soon wrote a poem, which was set to music similar to John Brown's Body, and resulted in the Battle Hymn of the Republic.
Alexander Hamilton Stephens, Vice President of the Confederate States of America, was imprisoned at Fort Warren for five months in 1865.
It is said the island has permanent inhabitants—ghosts. A guide book from just after the Civil War attributes this reference to troops being exposed to inclement weather. Many noises can be heard, and mystifying shadows appear, in a gale or tempest. Guard posts were eventually replaced with patrols, due to soldiers being hit by waves! The most famous story is about the Lady in Black.