Revolutionary War Manuscript Map of Fort Mifflin, with a Drawing of the Famous Continental Navy Jack Fort Mifflin Flag.
Finely-executed Revolutionary War manuscript plan and view of Fort Mifflin on Mud Island on the Delaware River, just below Philadelphia. Almost certainly produced by an engineer serving in William Howe’s army during the 1777 Philadelphia campaign, which ended with the reduction of Fort Mifflin after a terrible six-week siege.
The plan depicts Mud Island and Fort Mifflin at a large scale sufficient to show details of the Fort and surrounding defenses with all major features identified by a table of References at lower right. Of these, one of the more interesting is number 10, “Masonry, built by Majr Montresor Engr.”, more on whom below. At upper left is an inset perspective view of the Fort as seen from the south, somewhat downriver.
Over it flies an enormous American flag. This was the official flag of the Continental Navy, consisting of 13 alternating red, white and blue stripes, flown at Fort Mifflin because the Navy was operating on the river. According to one source the flag was so large it could be seen in Philadelphia, more than seven miles distant. By some miracle, it was still flying when the Fort’s American defenders abandoned the island on November 15, 1777.
The draftsmanship is both meticulous and expert, in the style of the military engineers of the period. The plan features careful lettering and delicate wash color, with different colors indicating variations in both ground cover and construction materials. On the inset view, the structures are well modeled and lit to give them a convincing three-dimensionality.
The plan is neither signed nor dated, and we have so far not matched the style or handwriting to other maps or plans with known draftsmen. However, the style, refined execution, and the references to “Rebels” in the title and John Montresor in the legend all indicate that the map was produced by a member of Howe’s army, almost certainly an engineer involved in the Philadelphia campaign.
Some clues point to George Walker Dyall Jones, an ensign in the 44th Regiment of Foot, as the mapmaker. This map was acquired with along with a Revolutionary War manuscript map of the Battle of Monmouth that was signed by Jones. His name is also found on four drawings at the Clements Library, including two with fort profiles like the one seen here. Furthermore, the 44 th , to which Jones was attached at the time of the battle, was stationed in Philadelphia in late 1777 – mid 1778. This attribution is complicated by the lack of a consistent, identifiable hand in any of the six maps and drawings signed by Jones. It is further complicated by a lack of information in the historical record about Jones’s military career before late 1778.
In 1771 the provincial government of Pennsylvania resolved to fortify Mud Island on the Delaware River, near the outlet of the Schuykill, a promising location for controlling the approaches to Philadelphia. At the request of Governor Thomas Penn, General Gage sent Captain John Montresor to Philadelphia to study the site and offer proposals. Montresor being an engineer, and the General Assembly being an elected government, all six of his proposals were deemed too expensive, though ultimately £15,000—far below the 40,000 required by Montresor’s preferred option—was appropriated.
In early 1772 Montresor oversaw the construction of masonry walls on the south and east (colored red and numbered “10” on our plan), but in June he returned to New York, leaving others to complete the work. Little else was accomplished until 1776, when the fort was completed at the order of Pennsylvania’s Revolutionary government. To Montresor’s walls were added barracks, a stockade, blockhouses and a “barricade” along the downriver end of the island, and a moat protecting the landward approaches. All are visible and labeled on the plan offered here. The Fort was protected by a line of obstacles (“chevaux de fries”) in the channel between Mud Island and the southeastern shore of the Delaware, and complemented by Fort Mercer and another fortification at Billingsport, both on the southeastern shore.
It was undoubtedly awareness of these fortifications that led the Brothers Howe to begin their Philadelphia campaign in July 1777 with a landing at the head of the Chesapeake Bay followed by an overland march, rather than attempting to force their way up the Delaware. That was only postponing a reckoning, however. After occupying Philadelphia on September 26, 1777, the Howes were still faced with the need to reduce the Delaware River fortifications. This they did in a costly campaign that lasted from October 2 through November 15, 1777, with Fort Mifflin the last to fall after suffering a long siege and the most vicious artillery bombardment of the war (It is said that at one point no fewer than 1000 shells struck the Fort in the space of an hour.) Ironically, Montresor himself, by now Chief Engineer to the British Army in North America, participated in the siege and devoted several pages to it in his Journals.
The present map was likely prepared during the siege or just after the Fort’s capture by the British. A few points help us establish the period during which the map could have been made, namely: number 6 in the “References” refers to “Barracks built of wood burnt by the Rebels” – this happened during the beginning of the battle; and the Continental Navy Jack is shown still flying over Fort Mifflin. The British were quick to take the flag down after the capture of the Fort, as the Continental Army had not struck their colors before retreating to New Jersey. Together these features give us a timeframe roughly from the middle of the battle to not long after its conclusion.
Other maps and plans of Mud Island
Mud Island was an immensely important fortification, and as such, was extensively mapped; we have located at least 13 extant manuscript plans of Mud Island and Fort Mifflin from the period, distributed among the Library of Congress (4), Clements Library (2), Cornell (4), Dartmouth (1 or 2) the Marburg (Germany) State Library (1)
and Yale (1). In addition, the first and second editions of William Faden’s Course of the Delaware River from Philadelphia to Chester offer large-scale inset plans of the Fort. All but the Cornell plans were drawn by members of the British military establishment; the four Cornell plans were drawn by French engineer Francois de Fleury, who served with the American defenders at Fort Mifflin.
We have inspected images of all but the Cornell plans (Having been produced by someone fighting on the American side, these plans are less relevant, as they are most unlikely to be either a source for or derivative of ours.) Looking across the extant plans, the depictions vary to a surprising degree. Even the 2 nd edition (1779) of the Faden map features an entirely new inset plan of the island, utterly different from that on the first edition. In particular, all of the plans inspected differ substantially from the one offered here, in both the format and details, and unlike ours none include a view.
We have also located a single view, held by the Library of Congress and possibly drawn by John Montresor, but it is differs utterly from the view inset at the upper left of our plan. Based on this examination, we tentatively conclude that our plan and the inset view should be considered unique, contemporary depictions of Mud Island and Fort Mifflin.
Since 2007 in the possession of a gentleman in Cypress, Texas. Gifted to him by one David A. Nicholson (1924-ca. 2016), who is said to have owned it since his youth in the United Kingdom.