The spies who helped win the Revolutionary War

"I only regret that I have but one life to lose for my country."

So wrote 21-year old Nathan Hale before being hanged for espionage by the British on Sept. 22, 1776. Hale had originally been encouraged to join the revolution by an old Yale classmate, Benjamin Tallmadge.

Tallmadge and Hale had been close during their time at Yale and often exchanged letters. Three years after their graduation, Tallmadge wrote to Hale, newly an officer in the American forces, saying, "Was I in your condition, I think the more extensive service would be my choice. Our holy Religion, the honor of our God, a glorious country and a happy constitution is what we have to defend."

Hale agreed with Tallmadge's sentiment and soon accepted an assignment to do more than just fight–he would spy from behind enemy lines. Although Hale's venture into espionage ended rather poorly, Tallmadge's revolutionary feelings did not subside. Soon, he would find himself at the center of the American Revolution's most important spy ring.

The Culper Ring, founded and supervised by Tallmadge, operated from late October in 1778 until the British evacuated New York in 1783. Although the ring was active for all five of these years, its most productive period was between 1778 and 1781.

Benjamin Tallmadge with his son, William.

After Tallmadge brought the ring together, it was led by Abraham Woodhull and Robert Townsend, codenamed "Samuel Culper, Sr." and "Samuel Culper, Jr." respectively. The codename "Culper" came straight from George Washington himself, a slight alteration of Culpeper County, Virginia where Washington had worked as a surveyor in his youth.

The ring was highly sophisticated, using methods still familiar today. Couriers, invisible ink. and dead drops were the norm. Some messages were hidden in plain sight, coded within newspaper advertisements and personal messages. Supposedly, one woman, Anna Strong, was even able to use the clothes she hung to dry to send messages to other members of the ring. Codes and ciphers were standard practice. These methods enabled agents to send Tallmadge apparently innocent letters. Tallmadge could pick out individual words to decode messages.

While Woodhull and Townsend ran the show, many agents, couriers, and sub-agents were also involved. Caleb Brewster, Austin Roe, Anna Strong and the still-unidentified 'Agent 355' all played vital roles. Other members included Hercules Mulligan and his slave Cato. Mulligan warned in January, 1779 of British plans to kidnap or kill senior American leaders including Washington himself. Cato delivered the vital message.

Other agents included Joseph Lawrence, Nathan Woodhull (Abraham's cousin), Nathaniel Ruggles, William Robinson and James Rivington. So solid was the ring's security that its very existence remained unconfirmed until the 20th century. Even Washington himself couldn't identify every Culper agent. Its strict security preserved both the ring and the lives of individual members, boosting their confidence in themselves and each other.

The Culper Ring's successes, what spies call coups, were many. They warned of a surprise attack on newly arrived French troops at Newport, Rhode Island. The forces, properly warned, were able to foil British plans to devastate their men while they recovered from their transatlantic voyage. The Culper spies uncovered British plans to destroy America's nascent economy by forging huge amount of Continental dollars. Continental dollars were soon withdrawn from circulation, replaced with coins by 1783.

Without the Culper Ring, Washington may have fallen for a raiding operation meant to divide his forces. In 1779, General William Tryon raided three main ports of Connecticut, destroying homes, goods in storage, and a number of public buildings. Tryon was attempting to split off a portion of Washington's forces to allow British forces to rout the Americans.

Washington did not ride out to meet Tryon. Instead, Tryon's forces rampaged through civilian land and the general was criticized by both American rebels and those who supported the British as barbarous.

By far the Culper Ring's most important coup was exposing General Benedict Arnold. Arnold, whose name has entered the American language as a metonym for treachery, was in contact with British spy Major John André and planned to surrender West Point to the British. The Culper Ring warned Tallmadge of a high-ranking American traitor, but lacked his identity. Tallmadge identified Arnold when André was captured and later hanged for his treason. Although Arnold escaped with his life, West Point remained safe from the British.

Benedict Arnold in 1776

Abraham Woodhull's sister Mary is sometimes credited with exposing Major André and thus Benedict Arnold. André (alias John Anderson) fled when he realized he was under suspicion. Unlike the Culper Ring's, André's security was lax. That cost André his life, Arnold his reputation, and ultimately helped cost the British Empire its American colony.

Stopped by three soldiers, André first tried to bribe them to let him go. Instead of taking the bribe, the soldier, now actively suspicious rather than idly curious, searched him and found incriminating papers. The letters proved conclusively that André was a British spy. The information contained in André's letters was almost useless to the British; their commander General Clinton already had it. They were, however, extremely valuable to Tallmadge.

André's captured messages were in Benedict Arnold's handwriting, making it suddenly clear who was leaking high-level information. Arnold fled for his life, going to England, then Canada. After alienating a number of business partners in New Brunswick, Arnold returned to England. André was not so lucky to escape the American forces–he would make a useful reprisal for the hanging of Tallmadge's dear friend, Nathan Hale. Caught dead to rights by the Culper Ring, André would soon be dead, period.

Hale had been hanged on Sept. 22, 1776 at the tender age of 21. He died bravely, with composure, courage and dignity. André faced the gallows equally bravely on Oct. 2, 1780. Before his death he received a visitor: Colonel Tallmadge.

The two spent part of their time together talking. At one point André asked Tallmadge whether his capture and Hale's were similar. Tallmadge, remembering his dead friend and perhaps feeling guilty at encouraging him to take a more active revolutionary role, replied, "Yes, precisely similar, and similar shall be your fate…".

The British evacuated New York in mid-August, 1783. On Nov. 16 of the same year, Washington himself visited to mark the seventh anniversary of the American retreat from Manhattan. While there he met someone to whom he and his new nation owed a personal and national debt: Culper agent Hercules Mulligan.

This article originally appeared on Explore The Archive. Follow @explore_archive on Twitter.