The Burr conspiracy was a suspected treasonous cabal of planters, politicians and army officers led by former U.S. Vice President Aaron Burr. According to the accusations against him, Burr’s goal was to create an independent nation in the center of North America and/or the Southwest and parts of Mexico. Burr’s explanation: To take possession of, and farm, 40,000 acres (160 km²) in the Texas Territory leased to him by the Spanish. When the expected war with Spain broke out, he would fight with his armed “farmers,” to seize some lands he could conquer in the war–all illegal by rules of warfare.
Jefferson and others had Burr arrested and indicted for treason with no firm evidence put forward. Burr’s true intentions are still considered ambiguous to some historians, who claim he intended to take parts of Texas and some or all of the Louisiana Purchase for himself. They claim Burr envisioned a new empire in the West over which he would rule. This historically unproven version of a conspiracy by Burr to take American land is still in print in many biographies, encyclopedias, and even history books. Letters written to this version can be found in letters by contemporaries who distrusted Burr, but no solid evidence can be found.
In November 1805, Burr again met with Merry and asked for two or three ships of the line and money. Merry informed Burr that London had not yet responded to Burr's plans which he had forwarded the previous year. Merry gave him fifteen hundred dollars. Those Merry worked for in London expressed no interest in furthering American secessionism.
In the spring of 1806, Burr had his final meeting with Merry. In this meeting Merry informed Burr that still no response had been received form London. Burr told Merry, "with or without such support it certainly would be made very shortly. Merry was recalled to Britain on June 1, 1806.
In 1805, Burr travelled throughout Louisiana. In the spring, Burr meet with Harman Blennerhassett. Blennerhassett proved a valuable tool in helping Burr further his plan. He provided friendship, support, and most importantly access to the island that he owned on the Ohio River, about 2 miles (3 km) below what is now Parkersburg, West Virginia. In 1806, Blennerhassett offered to provide Burr with substantial financial support. Burr and his co-conspirators used this island as a storage space for men and supplies. Burr tried to recruit volunteers to enter Spanish territories. In New Orleans, he met with the Mexican Associates, a group of ’’criollos’’ whose objective was to conquer Mexico. Burr was able to gain the support of New Orleans’ Catholic bishop for his expedition into Mexico.
Reports of Burr's plans first started to appear in newspapers in August where it was insinuated that Burr intended to raise a western army and "to form a separate government".
In early 1806, Burr contacted the Spanish minister Carlos Martinez de Yrujo who Burr told that his plan was not just western succession, but the capture of Washington, D.C.. Yrujo wrote to his masters in Madrid about the coming "dismemberment of the colossal power which was growing at the very gates of New Spain. Yrujo gave Burr a few thousand dollars to get things started. The Spanish government in Madrid took no action.
Following the events in Kentucky, Burr went back west later into 1806 with the hope of recruiting more volunteers for a military expedition down the Mississippi River. Here he recruited Blennerhassett and began using his island, Blennerhasset Island, to store men and supplies. The Governor of Ohio grew suspicious of the activity on the island, and ordered the state militia to raid the island and seize all supplies. Blennerhasset managed to escape with one boat, and he met up with Burr at the operation’s Headquarters on the Cumberland River. With a significantly smaller force, the two headed down the Ohio River to the Mississippi River and New Orleans. Wilkinson had vowed to supply troops at New Orleans; however, he had come to the conclusion that the conspiracy was bound to fail, and rather than providing these troops, Wilkinson revealed Burr’s plan to President Jefferson.
In February and March, 1806, Jo Daviess, United States District Attorney for Kentucky wrote Jefferson several letters warning him of possible conspiratorial activities by Burr. Daveiss’ July 14 letter to Jefferson stated flatly that Burr planned to provoke a rebellion in Spanish-held parts of the West in order to join them to areas in the Southwest to form an independent nation under his rule. Similar accusations were appearing against local Democratic-Republicans in a Frankfort, Kentucky newspaper, Western World, and Jefferson dismissed Daveiss’s accusations against Burr, a Democratic-Republican, as politically motivated.
Rumors of political instability in the West finally forced themselves upon Jefferson and his cabinet, with their suspicions being confirmed when Wilkinson sent him correspondence received from Burr. In an attempt to preserve his innocence and career, Wilkinson edited these correspondences. The letters had been sent to Wilkinson in cypher, however he altered the letter to prove both his "innocence" and Burr's guilt. He warned Jefferson that Burr was “meditating the overthrow of [his] administration” and “conspiring against the State.” Jefferson alerted Congress of the plan, and ordered the arrest of anyone who conspired to attack Spanish territory. He warned authorities in the West to be aware of suspicious activities. Convinced of Burr’s guilt, Jefferson ordered his arrest. Burr fled to the Mississippi Territory, where he was apprehended. He managed his escape from the searchers and was recaptured in February, 1807 and confined at Fort Stoddert. While in transport to Washington D.C. he again attempted escape in South Carolina, but failed.
Burr was charged with treason for assembling an armed force to take New Orleans and separate the Western from the Atlantic states. He was also charged with high misdemeanor for sending a military expedition against territories belonging to Spain. George Hay, the prosecuting U.S. Attorney, complied a list of over 140 witnesses, one of whom was Andrew Jackson. In order to encourage witness participation, it is said that Thomas Jefferson gave Hay sheets of blank pardons.
The case met oppostition from the beginning, with the high misdemeanor charge being dropped when the government was unable to prove that the expedition had been military in nature or directed towards Spanish territory.
Burr’s trial brought into question the ideas of executive privilege and the independence of the executive. Burr’s lawyers, including John Wickham, asked Chief Justice John Marshall to subpoena Jefferson, claiming that they needed documents from Jefferson in order to accurately present their case. Jefferson proclaimed that as President, he reserved the right to decide “what papers coming to him as President, the public interests permit to be communicated [and] to whom.” He insisted that all relevant papers had been made available, and that he was not subject to this writ because he held executive privilege. He also argued that he should not be subject to the commands of the judiciary, because the constitution guaranteed the executive branch’s independence from the judicial branch. Marshall sided with Burr, deciding that the subpoena could be issued despite Jefferson’s position of presidency. Though Marshall vowed to consider Jefferson’s office and avoid “vexatious and unnecessary subpoenas,” his ruling was significant because it suggested that like all citizens, the President was subject to the law.
Burr’s case required Marshall to consider the definition of treason. It raised the question of whether or not intent was enough to convict someone of treason. Marshall ruled that because Burr had not committed an act of war, he could not be found guilty. Because the First Amendment guaranteed Burr the right to voice opposition to the government, “merely suggesting war or engaging in a conspiracy was not enough to require a conviction.” In order to be convicted of treason, Marshall ruled, an overt act of participation must be proven with evidence. Intention to divide the union was not an overt act: “There must be an actual assembling of men for the treasonable purpose, to constitute a levying of war.” Marshall further supported his decision by indicating that the Constitution stated that two witnesses must see the same overt act against the country. Marshall, however, narrowly construed the definition of treason provided in Article III of the Constitution; he noted that the prosecution had failed to prove that Burr had committed an "overt act," as the Constitution required. As a result, the jury acquitted the defendant, leading to increased animosity between the President and the Chief Justice.
Following this incident, James Wilkinson was twice investigated by Congress. Following an unsuccessful court-martial, ordered by President James Madison in 1811, he returned to his military command in New Orleans. During the War of 1812, he was posted to Canada where his only major offensive , a campaign against Montreal, was unsuccessful. He was discharged from active service. Wilkinson died in Mexico on December 28, 1825.
When the conspiracy was uncovered, Harman Blennerhassett's mansion and island were occupied and allegedly plundered by members of the Virginia Milita. He fled with his family and was twice arrested. The second time he remained imprisoned until Burr was acquitted. He went to Mississippi and became a cotton planter and later moved to Montreal where he practiced law. Blennerhassett returned to his native Ireland where he died on February 2, 1831.