An 18th-century fort, now a museum

A half-built British fort survives a brutal siege

Fort Mifflin is an 18th-century fort on the Delaware River, now run as a museum. Its stone walls and brick casemates still sit on Mud Island, with Philadelphia International Airport close by across the water.

The fort began as a British plan. In 1771, Captain John Montresor of the British Corps of Engineers designed it for Pennsylvania's colonial government, which wanted to control shipping on the river. Montresor wanted thirty-two cannons and a garrison of four hundred men. The commissioners who paid for it balked at the cost and cut his budget. Work crawled along for about a year. Montresor left in 1772, frustrated, and never returned. Only the east and south walls were finished, in stone, before the money ran out.

Six years later, the unfinished fort became a battlefield. During the Siege of Fort Mifflin, British ships and land batteries bombarded it for weeks in the fall of 1777, firing more than ten thousand cannonballs. Lieutenant Colonel Samuel Smith commanded fewer than five hundred men inside. Nearly 350 Americans died defending it before the garrison finally abandoned the ruins in November.

The Army rebuilds the fort and renames it

The fort lay in ruins after 1777 until the U. S. Army started rebuilding it in 1794, renaming it for Thomas Mifflin, Pennsylvania's first governor after independence. Soldiers and engineers kept adding to it through the early 1800s, turning Montresor's unfinished walls into a real coastal defense.

Confederate prisoners die and a hanged deserter follows

During the Civil War, Fort Mifflin held Confederate prisoners of war, many of them captured after Gettysburg. Conditions inside the casemates were grim. Spoiled meat, bad sanitation and dysentery spread through the cells, and three prisoners died there. In 1863, prisoners staged a rebellion. The next February, Union deserter William H. Howe led roughly two hundred prisoners in a tunnel escape from Casemate #5. It failed.

Howe himself did not escape justice for long. He had shot and killed an enrolling officer sent to arrest him for desertion at his Pennsylvania home. The Army tried him, convicted him of murder, and hanged him at Fort Mifflin on August 26, 1864. The public was allowed to pay for a ticket to watch. He was the only person executed at the fort during the war.

The fort stays in military service for two centuries

The Army kept Fort Mifflin in service long after the war ended, garrisoning and building on the site into the 20th century. It remained an active military post for nearly two more centuries, making it one of the oldest forts the U. S. Military ever used continuously. The Army finally decommissioned it for active infantry and artillery duty in 1962.

A landmark fort reopens as a museum and venue

The City of Philadelphia took over the older part of the fort, while the U. S. Army Corps of Engineers kept using a portion of the grounds, a use that continues today. In 1970, Fort Mifflin was named a National Historic Landmark and listed on the National Register of Historic Places. Pennsylvania added its own historical marker in 1990.

A legend tells of a woman named Elizabeth Pratt, said to have hanged herself in the Officers' Quarters after losing children to illness, her screams still heard on the grounds. The fort is still counted among the most haunted sites in the country, with visitors and staff reporting voices, footsteps and apparitions of soldiers since the 18th century.

Today, Fort Mifflin runs as a museum, with its stone walls, casemates and earthworks open to visitors. It hosts candlelight ghost tours each October, along with overnight paranormal investigations and a Renaissance faire each spring. A dance music festival has drawn crowds to the grounds in recent years, filling the same walls that once held a desperate garrison and Confederate prisoners.