Anger over the acquisition of Louisiana led some Federalists to consider secession as a last resort to restore their party's former dominance. One group of Federalist congressmen plotted to establish a "Northern Confederacy" which would consist of New Jersey, New York, the New England states, and Canada. Alexander Hamilton repudiated this scheme, and the conspirators turned to Vice President Aaron Burr. In return for Federalist support in his campaign for the governorship of New York, Burr was to swing the state into the confederacy. Burr was badly beaten, in part because of Hamilton's opposition. Incensed, Burr challenged Hamilton to the duel in which the Federalist leader was fatally wounded.
As a result of the duel, Burr was ruined as a politician. New Jersey and New York indicted the Vice President on murder charges; the charges were later quashed. The desperate Burr then became involved in a conspiracy for which he would be tried for treason.
In the Spring of 1805, Burr and James Wilkinson (1757-1825), the military governor of Louisiana, hatched an adventurous scheme, the exact nature of which remains unknown. The British minister was told that for $500,000 and British naval support, Burr would separate the states and territories west of the Appalachians from the Union and create an empire with himself as head.
In the fall of 1806, when Burr and some 60 conspirators traveled down the Ohio River toward New Orleans, Wilkinson betrayed the former Vice President. He sent a letter to Jefferson describing a "deep, dark, wicked, and widespread conspiracy...to seize New Orleans, revolutionize the territory, and carry an expedition against Mexico." Burr fled, but was apprehended and tried for treason, with Chief Justice John Marshall presiding. Under the Constitution, each act of treason must be attested to by two witnesses. The prosecution was unable to meet this strict standard and Burr was acquitted.
Was Burr guilty of conspiring to separate the West? Probably not. The prosecution's case rested on the unreliable testimony of co-conspirator Wilkinson, who was a spy in the pay of Spain. It appears that Burr was planning an unauthorized military attack on Mexico, then under the control of Spain. The dream of creating an "empire for liberty" appealed to many Americans who feared that a European power might seize Spain's New World colonies unless Americans launched a preemptive strike. Hamilton himself had aspired to raise a huge army to invade and conquer Spanish territories. To the end of his life, Burr denied he had plotted treason against the United States.
In this letter, former President Adams expresses his interest in the outcome of Burr's treason trial.
am anxious to see the Progress of Burr's Tryal: not from any Love or hatred I bear the man, for I cannot say that I feel either.... But I think Something must come out of the Tryal, which will strengthen or weaken our Confidence in the General Union. I hope something will appear to determine clearly whether any foreign Power has or has not been tampering with our Union.... [Burr's actions] could be instigated only by his own ambitious avarice or Revenge. But I hope his Innocence will be made to appear, and that he will be fairly acquitted.…