Betrayal, Treason, and the Fall of an American Founder

In ‘This Week in History,’ a disgraced Aaron Burr forges an unscrupulous alliance against Spain, leading to one of the nation’s most famous trials.

A portrait of Aaron Burr by John Vanderlyn, 1803. Public Domain

Alexander Hamilton was dead and buried, killed by a gun fired by Aaron Burr. At the height of his political power, Burr had killed Hamilton, and, much like Hamilton on the day he was shot, July 11, 1804, Burr’s political life would enter its death throes on July 12—the day Hamilton died.

Burr had witnessed a steady rise politically, from joining the Continental Army during the Revolutionary War to becoming attorney general for New York, then serving as a senator from 1791 to 1797. He was one vote shy of winning the 1800 presidential election and, therefore, had to settle for the vice presidency under Thomas Jefferson. Burr, however, had spurned too many political foes and allies alike, and, after the duel with Hamilton, his rise had come to an end.

Anonymous 1902 illustration depicting the duel between Aaron Burr and Alexander Hamilton, which occurred on July 11, 1804. Public Domain

After Hamilton’s death, both New York and New Jersey indicted him for murder, though he never stood trial. Burr returned to Washington to finish out his term as vice president and president of the Senate. The latter proved monumental, as he oversaw the impeachment trial of Supreme Court Justice Samuel Chase, which had been instigated by Jefferson. The Senate acquitted Chase on March 1, 1805.

The following day, Burr stood before the Senate and announced his resignation to the Senate. He had been replaced by George Clinton, of New York, for vice president during the 1804 election. His party, the Democratic-Republicans, had seen the writing on the wall. Burr’s resignation came two days before Jefferson began his second term. Burr proclaimed that the Senate

“is a sanctuary; a citadel of law, of order, and of liberty; and it is here—it is here, in this exalted refuge; here, if anywhere, will resistance be made to the storms of political phrenzy and the silent arts of corruption; and if the Constitution be destined ever to perish by the sacrilegious hands of the demagogue or the usurper, which God avert, its expiring agonies will be witnessed on this floor.”

It appears Burr was referencing Jefferson (and even perhaps his long-time and now-dead political rival, Hamilton, who had held immense sway over the Federalist Party). His words, however, would soon deal specifically with himself, and he would be standing in court accused of being “the usurper.” But the Constitution, with its definition of treason, ensured he did not prematurely join Hamilton in the grave.

Go West

Burr’s political life in the East was over, and he now looked to the new lands in the West. On April 30, 1803, the Louisiana Purchase was signed, practically doubling the size of the United States. This new territory seemed ripe for political leaders, and Burr, known for his ambition, pursued the opportunity.

Before the Louisiana Purchase, the territory had switched hands between the Spanish and French. Even after the Franco-Spanish Treaty of Ildefonso, which “retroceded” the territory back to the French, it remained under Spanish administration. The Spanish tried to resist the expanding Americans, even cutting off the Mississippi River and the port of New Orleans. After the Louisiana Purchase, there remained ambiguity about the exact borders between Spanish and American lands. The ambiguity did not deter settlers.

James Wilkinson, a morally ambiguous American figure, had served in the Continental Army, been part of the Conway Cabal against Gen. George Washington, and by 1784 had moved to Kentucky and began negotiations with the Spanish regarding independence for Kentucky. The threat of settlers turning territories into new nations was a constant worry for the American government. In 1787, Wilkinson had secretly sworn allegiance to the Spanish governor (a fact not officially uncovered until the 20th century), and his penchant for split loyalties became pronounced in his dealings with Burr.

Putting a Plan in Place

After his time in the nation’s capital ended, Burr was confronted with the dichotomy between opportunity and loyalty. He chose the former—a seemingly natural inclination for Burr. During the same month as his resignation, he met with Anthony Merry, the British minister to the United States. According to Merry, the two met in Philadelphia to discuss how “the inhabitants of Louisiana seem determined to render themselves independent of the United States and the execution of their design is only delayed by the difficulty of obtaining previously an assurance of protection and assistance from some foreign power. ... It is clear that Mr. Burr means to endeavor to be the instrument for effecting such a connection. ... Mr. Burr observed it would be too dangerous and even premature to disclose to me at present the full extent and detail of the plan he had formed.”

A plan, however, was being formed. He had suggested to Merry that he would require several frigates at the mouth of the Mississippi River to prevent an American blockade, as well as a loan of about 100,000 pounds.

Burr then left Philadelphia to inspect the western lands. He arrived in Pittsburgh at the end of April, planning to meet his old friend, Wilkinson. The meeting had to wait as Wilkinson, currently serving as the territorial governor of Louisiana, was delayed. Burr, therefore, boarded a 60-foot houseboat and made his way down the Ohio River.

On May 5, 1805, he stopped at the four-mile long Blennerhassett Island, where he dined with the wealthy Irish immigrant, Harman Blennerhassett, and his family. He remained at the island mansion until 11 p.m., discussing his plans. These plans involved Blennerhassett turning his mansion into Burr’s military headquarters. Blennerhassett wrote, “I am disposed, in the confidential spirit of this letter, to offer you and my friends’ and my own services in any contemplated measures in which you may embark.”

Blennerhassett Island from the north, as seen today. WVhybrid/CC BY-SA 3.0

Burr continued down the Ohio River, stopping in Cincinnati and Nashville before arriving at Fort Massac, located on the river at the southern tip of Illinois today. Here, he met Wilkinson, whom he had been communicating with via coded letters based on a cipher system Wilkinson had created.

Along with a barge, Wilkinson provided Burr a letter of introduction for his arrival in New Orleans. Upon entering in the port city, Burr made the acquaintance of a wealthy merchant, Daniel Clark, who, on Burr’s behalf, began inquiring about the strength of local Spanish forts and the public sentiment toward a Mexican irruption from Spain. He also promised $50,000 towards Burr’s imperial expedition with the hopes of becoming “a duke” in the new Burr empire.

For the rest of 1805, Burr continued his survey of the western lands, furthering discussions with Wilkinson, making more contacts, even returning to Washington to dine with Jefferson. He wrote his first letter to Blennerhassett, ordering him to turn his island into a military encampment. As 1805 turned into 1806, and the winter months gave way to spring, Burr continued the pursuit of his ambitious expedition, even taking the major step of contracting more than 20 boats to be built to accommodate 500 men, along with supplies. He also purchased 400,000 acres near the Washita River in today’s northern Texas.

The Unraveling

In August 1806, however, his idea began to unravel when he discussed his goals with Col. George Morgan. Morgan, completely shocked by Burr’s comments, sent a letter to Jefferson, informing him of Burr’s plans—it was the first Jefferson had heard of the plan.

When Wilkinson received Burr’s latest correspondence about his impending arrival with armed men, he suddenly soured on Burr’s plans and sent a letter of warning to Jefferson. He informed the president that an expedition planned to sail from New Orleans in February and land at Vera Cruz.

The federal government had worked long and hard to resume peaceful relations with Spain. Jefferson, concerned that would be undone by this seemingly imminent invasion, called out militias and federal officials to find and administer the appropriate punishment for “all persons engaged or concerned in such enterprise.”

Most of the boats built for the invasion were confiscated shortly before their departure. Many of the armed men who planned to be involved now either dispersed or were too disappointed in the recent outcomes to continue. Burr, arriving with Blennerhassett and a remnant of his confederates in Bayou Pierre, just north of New Orleans, discovered Wilkinson’s betrayal. Burr immediately issued a statement of innocence, but that hardly mattered.

While camping along the Natchez River, Burr received a letter from the governor of the Mississippi Territory requiring he surrender and stand before a grand jury. He arrived in Washington, a town in the Mississippi Territory, and stood before a grand jury, which quickly acquitted him. Burr was subsequently released.

A Case of Treason

As more rumors and facts about Burr’s actions circulated, another warrant for his arrest was issued. Burr planned to take refuge in Florida, but while in Alabama, he was arrested and taken by a nine-man military escort to Richmond. On March 26, he stood before Chief Justice John Marshall, now known as the Father of the Supreme Court.

A photo from 1904 shows the place Burr was captured near Wakefield, Ala. Internet Archive Book Images/CC BY-SA 2.0

According to contemporary historian, Allan B. Magruder, “After an examination and arguments, which consumed three days, the chief justice decided to commit the prisoner on the charge of misdemeanor for having set on foot a military expedition against Mexico. ... The charge of high treason was reserved for investigation by the grand jury.”

Burr’s bail was set for $10,000, which was paid by several locals, thus freeing Burr from custody. It was during this week in history, on May 22, 1807, that Burr was brought before the grand jury for the charge of treason. The trial itself, however, did not begin until Aug. 3, primarily due to waiting for one of the trial’s primary witnesses: James Wilkinson.

When the trial began, Marshall made it abundantly clear that the charge of treason must adhere strictly to the Constitution’s definition, that “Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.”

Chief Justice John Marshall, oil on canvas painting by Rembrandt Peale, 1834. Public Domain

The case became one of America’s most famous, involving some of the nation’s most famous, infamous, and important figures, including Burr; Marshall; Wilkinson; co-conspirator Jonathan Dayton, who was the youngest signer of the Constitution; Burr’s defense council, which included Edmund Randolph, a former secretary of state and a delegate at the Constitutional Convention and Charles Lee, a former attorney general; the prosecution, which included the future attorney general, William Wirt; and, to an extent, Jefferson, who had unprecedentedly been sent a subpoena by Marshall for papers concerning the case.

On Sept, 1, 1807, the jury concluded that “Aaron Burr is not proved to be guilty under this indictment by any evidence submitted to us. We therefore find him not guilty.”

Whether Burr committed treason by attempting to create another country on the continent, or if he solely planned an ill-conceived invasion of Mexican lands remains a topic of debate to this day.

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