The Harbor Defenses of the Delaware was a United States Army Coast Artillery Corps harbor defense command. It coordinated the coast defenses of the Delaware River estuary from 1897 to 1950, beginning with the Endicott program. These included both coast artillery forts and underwater minefields. The areas protected included the cities of Philadelphia, Camden, and Wilmington along with the Chesapeake & Delaware Canal. The command originated circa 1896 as an Artillery District and became the Coast Defenses of the Delaware in 1913, with defenses initially at and near Fort Delaware on Pea Patch Island near Delaware City. In 1925 the command was renamed as a Harbor Defense Command. During World War II the defenses were relocated to Fort Miles on Cape Henlopen at the mouth of the Delaware Bay.Stanton, pp. 455-481Coast Artillery Organization: A Brief Overview at the Coast Defense Study Group websiteRinaldi, pp. 165-166Berhow, pp. 427-434
History Early forts on the Delaware River Colonial period
Europeans came to the Delaware Valley in the early 17th century, with the first settlements founded by the Dutch, who in 1623 built Fort Nassau on the Delaware River (which they called the South River, or Zuyd Rivier in Dutch) opposite its confluence with the Schuylkill River in what is now Brooklawn, New Jersey. Fort Nassau was a factorij or fortified trading post. The Dutch considered the entire Delaware River valley to be part of their New Netherland colony, which extended from what is now southern Delaware to Rhode Island. In 1638, Swedish, Finnish, and renegade Dutch settlers led by Peter Minuit established the colony of New Sweden at Fort Christina (present-day Wilmington, Delaware) and quickly spread out in the valley. In 1644, New Sweden supported the Susquehannocks in their military defeat of the English colony of Maryland. In 1648, the Dutch built Fort Beversreede on the west bank of the Delaware, south of the Schuylkill near the present-day Eastwick neighborhood, to reassert their dominion over the area. The Swedes responded by building Fort Nya Korsholm, or New Korsholm, after a town in Finland with a Swedish majority. In 1655, a Dutch military campaign led by New Netherland Director-General Peter Stuyvesant took control of the Swedish colony, ending its claim to independence. The Swedish and Finnish settlers continued to have their own militia, religion, and courts, and to enjoy substantial autonomy under the Dutch. The English conquered the New Netherland colony in 1664, though the situation did not change substantially until 1682 when the area was included in William Penn's charter for Pennsylvania, under which the city of Philadelphia was founded. Penn's colony originally included both Pennsylvania and Delaware; by 1704 the latter split off as the colony of Lower Delaware, though the two shared a common governor.
William Penn and many of the Pennsylvania colonists were Quakers, members of a pacifist Christian sect. They fostered good relations with Lenape (Delaware) tribe, purchasing the colony's land from them, and had the only significant European settlements in the Americas without fortifications. In the 1740s French and Spanish privateers entered the Delaware River, threatening the city. During King George's War (1744–1748), Benjamin Franklin raised a militia called the Association for General Defense, because the legislators of the city decided to take no action to defend Philadelphia "either by erecting fortifications or building Ships of War". He raised money to create earthwork defenses and buy artillery. The largest of these was the "Association Battery" or "Grand Battery" of 50 guns, on the site that became Joshua Humphreys' shipyard in 1794 and is now the Coast Guard Station Philadelphia. At the end of the war, commanders disbanded the militia and left derelict the defenses of the city. With the outbreak of the French and Indian War (part of the Seven Years' War) in the 1750s, plans were drawn up for a fort on Mud Island (later called Fort Mifflin) in the Delaware at the southern end of today's city limits, but no fort was built. Eventually, in 1771 British General Thomas Gage assigned Captain John Montresor of the British Corps of Engineers to the task of designing and building a fort on the island. Montresor submitted six designs to Penn and the Board of Commissioners, estimating £40,000 for an adequate fort with 40 guns and a 400-man garrison. His designs were all considered too expensive by the Board, which provided only £15,000 for purchasing the island and building the fort. Construction began in 1771, but in mid-1772 Montresor left the project and returned to New York. Work on the fort ended a year later, with only the east and south walls built.
Revolutionary War
In April 1775 the American Revolution broke out full-scale at Lexington and Concord in Massachusetts. These battles were followed shortly by the convening of the Second Continental Congress in Philadelphia on May 11, 1775. The Philadelphia Committee of Safety, headed by Benjamin Franklin, decided to protect the city by obstructing British access to the Delaware River. Three forts were built to protect two lines of chevaux de frise obstacles in the river, designed by Robert Smith. One line was at Fort Billingsport, New Jersey, and another was between Fort Mifflin (called "Fort on Mud Island" or the "Fort Island Battery" at the time) and Fort Mercer. A third line of obstacles was downstream at Marcus Hook with no forts nearby. Forts Mercer and Billingsport in New Jersey were designed by Tadeusz Kościuszko and built as earthworks; work also resumed on Fort Mifflin and all three forts were garrisoned during 1777. Meanwhile, the Continental Congress relocated to Baltimore in early 1776 due to a threat of British attack, later returning to Philadelphia and issuing the Declaration of Independence on July 4, 1776, attracting further British attention to the city.
In early 1777 the British planned to cut New England off from the rest of the colonies by sending a force under John Burgoyne southward from Montreal through the Lake Champlain area and the Hudson Valley to Albany. This was intended to be supported by a force under General William Howe advancing northward from New York City. However, George Germain, a British civilian official managing the war in London, also gave approval for Howe to capture Philadelphia. Howe proceeded with the Philadelphia plan and largely failed to support Burgoyne's campaign. The Philadelphia campaign was time-consuming but successful; the British took a lengthy water route through Chesapeake Bay, then marched overland to defeat Washington at the Battle of Brandywine southwest of Philadelphia on September 11, and entered the city unopposed on September 26. The Continental Congress left the city ahead of the British occupation, moving first to Lancaster and then to York, Pennsylvania.
Howe had the luxury of bypassing most of Philadelphia's defenses, occupying the city following his victory at Brandywine. However, his primary supply route was the Delaware River, with the forts and lines of chevaux de frise blocking it. They cut through the line near Marcus Hook without opposition, and easily took Fort Billingsport and its line of obstacles on October 2. They then laid siege to Fort Mifflin and Fort Mercer, unsuccessfully attacking the latter by land and river in the Battle of Red Bank on October 22. The 1,200 Hessians of the assault force suffered over 350 casualties, the British also losing (64 guns) and HMS Merlin (18 guns) to grounding.Fort Mercer at RevolutionaryWarNewJersey.com The latter was possibly an indirect result of engagement by the Continental and Pennsylvania navies, which also provided enfilading fire against the Hessians. The siege was commanded by John Montresor, designer of Fort Mifflin. On November 10 bombardment of the fort began in earnest. The fort was evacuated and burned (to impede its use by the British) five days later, with the Patriot forces of over 400 men suffering about 250 casualties. Fort Mifflin was "entirely beat down; every piece of cannon entirely dismounted", as reported by George Washington. On November 18, Fort Mercer was evacuated in the face of a British force of 2,000, their artillery having breached the fort's walls.
Burgoyne's campaign came to a defeat in the Battles of Saratoga, leading to his eventual surrender on October 17. This victory persuaded France to enter the war on the Patriot side. Word of it reached Commissioner Benjamin Franklin in Paris on December 4, and negotiations resulted in France declaring war on Britain in March 1778.
Washington and his army encamped at Valley Forge in December 1777, about 20 miles (32 km) from Philadelphia, where they stayed for the next six months. Over the winter, 2,500 men (out of 10,000) died from disease and exposure. However, the army eventually emerged from Valley Forge in good order.Douglas Southall Freeman, Washington (1968) pp. 381–82
Meanwhile, there was a shakeup in the British command. General Howe resigned his position, and was replaced by Lieutenant General Henry Clinton as commander-in-chief. France's entry into the war forced a change in British war strategy, and Clinton was ordered by the government to abandon Philadelphia and defend New York City, now vulnerable to French naval power. Clinton shipped many Loyalists and most of his heavy equipment by sea to New York, and evacuated Philadelphia on June 18, 1778. Washington's army shadowed Clinton's, and Washington successfully forced a battle at Monmouth Courthouse on June 28, the last major battle in the North. Washington's second-in-command, General Charles Lee, who led the advance force of the army, ordered a controversial retreat early in the battle, allowing Clinton's army to regroup. By July, Clinton was in New York City, and Washington was again at White Plains, New York. Both armies were back where they had been two years earlier.
The military focus of the war shifted to the southern colonies. Eventually, the American victory in the Yorktown campaign on October 19, 1781 proved to be the key to independence; the British received word of it on November 25. This precipitated a collapse of Lord North's Tory government in March 1782. The new Whig government suspended offensive operations in the Thirteen Colonies and commenced lengthy peace negotiations, culminating in the Treaty of Paris that ended the war on September 3, 1783.
1783–War of 1812 The ruins of Fort Mifflin lay derelict until 1793, when rebuilding began under what was later called the first system of US coastal fortifications. Pierre L'Enfant, also responsible for planning Washington, D.C., supervised the reconstruction and designed the rebuild in 1794. Reconstruction work began on the fort in 1795 under the auspices of engineer officer Louis de Tousard, who from 1795 to 1800 worked on coastal defenses between Massachusetts and the Carolinas. The initial goal was to rebuild the fort to accommodate 48 guns. The army officially named the fort after Thomas Mifflin, a Continental Army officer and the first post-independence Governor of Pennsylvania, in 1795. Rebuilding the fort consumed $94,000 of a total fort budget of $278,000 in 1798 and 1799 alone (in 1799 money). Also, the U.S. Congress met in Philadelphia until 1800 and Fort Mifflin was well garrisoned until then, usually with two companies.