Philadelphia Spy Ring Keeps Washington Informed (NOV 1777)

Photo By Lori Stewart | 1778 plan of Fort Mifflin showing the British batteries on Province Island in the lower right (Library of Congress)  

UNITED STATES

11.13.2023

Story by Lori Stewart 

U.S. Army Intelligence Center of Excellence

by Lori S. Stewart, USAICoE Command Historian

NOVEMBER 1777
In mid-November 1777, Maj. John Clark, Jr.’s Philadelphia spy ring kept General George Washington regularly updated on British movements toward Fort Mifflin and Fort Mercer on the Delaware River. Clark’s timely reports allowed the garrisons of both forts to evacuate before British ground forces arrived.

After taking over Philadelphia on 26 September 1777, British General William Howe quickly realized how disadvantaged his forces were in the former American capital. As winter approached, the British desperately needed supplies and hoped to attack Washington’s army before it reached its winter quarters at Valley Forge. Yet, two American forts—Fort Mifflin and Fort Mercer—blocked the Delaware River seven miles south of the city.

Washington needed clearer information about British plans to attack the two forts. Fortunately, with forethought, Washington had sent Maj. Gen. Thomas Mifflin to Philadelphia to organize a spy network in April. Mifflin promptly turned the ring’s operation over to Major Clark, a 26-year-old Pennsylvanian lawyer. Clark had joined the army the previous summer and, through the fall of 1776, had reconnoitered British positions on Long Island at Washington’s request. At that time, he had passed his reports to Maj. Benjamin Tallmadge, the military contact for Washington’s civilian intelligence chief, Nathaniel Sackett. Tallmadge would later form the renowned Culper Spy Ring that operated on Long Island. [See "This Week in MI History" #4 25 August 1778] Clark, however, shifted his efforts closer to his childhood home in the late spring of 1777.

In Philadelphia, Clark built a large network of loyal, unassuming men and women, including farmers, merchants, and others in high society who regularly mingled with British officers. Through constant observation, they gathered information on enemy troop movements and numbers, naval maneuvers, artillery emplacements, checkpoints, morale, and supply issues. In early October, Clark focused his spy ring on determining British intentions for Fort Mifflin, located on Mud Island in the middle of the Delaware, and Fort Mercer at Red Bank on the New Jersey side of the river.

In mid-October, the British launched a naval and ground assault on both forts that quickly ground down after heavy British losses. Then, on 3 November, one of Clark’s spies overheard British officers discussing a new attack on the two forts but learned no firm date. A week later, Howe renewed the naval bombardment of Fort Mifflin. Ground forces under General Lord Charles Cornwallis, however, were delayed. One of Clark’s men outside Philadelphia reported Cornwallis would begin his march down the west bank of the river on 15 November.

Meanwhile, at Fort Mifflin, Lt. Col. Samuel Smith and his four hundred soldiers had been ordered by Washington to hold the post “to the last extremity.” By the 15th, having weathered five days of cold rain and unrelenting cannon fire—the largest bombardment of the American Revolution—the Americans were nearly out of ammunition as 2,000 Redcoats approached. Consequently, late that night, Maj. Simeon Thayer, who had replaced a wounded Colonel Smith, ordered the fort set afire and his men quietly rowed across the Delaware to Fort Mercer. They left the American flag flying.

When Cornwallis arrived to find Fort Mifflin abandoned, he turned his attention on Fort Mercer. For several days, Clark and his spies kept General Washington continually apprised of the British movements, often before they happened. The Fort Mercer garrison fought until Cornwallis and his reinforcements were nearly at their gates and then quietly evacuated the night of 20 November.

While the loss of the two forts was a blow to the Continental Army, their reduction had engaged the British long enough to allow Washington to move his army to Valley Forge safely. Major Clark, exhausted from three months of continuous action, returned home in December. His network, however, continued to provide Washington information until the British vacated Philadelphia in June 1778.

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• Date Taken: 11.13.2023
• Date Posted: 11.13.2023 09:29
• Story ID: 457701
• Location: US