Although Thomas Jefferson (1743-1826) had already retired from politics by the time the war began, policies that developed during his presidential term influenced the timing and the outcome of the war.
In the early 19th century, U.S. trading vessels were caught in the crossfire between British and French trade blockades. Americans were outraged by infringements of U.S. maritime rights and Jefferson's administration retaliated with reciprocal embargoes. For instance, in 1806, Congress agreed to prohibit the importation of certain British goods.
President Jefferson realized the gravity of the growing tensions with Britain and wanted to take preparatory measures. He developed a plan of defense to bolster the American forces, which included reorganizing state militias and building 74-gun ships. Congress was however, only mildly interested in supporting Jefferson's proposals.
The Chesapeake affair, during which several American sailors were effectively abducted by the British Navy, brought the U.S. and Britain to the brink of war. Jefferson called out the militia to defend the coasts, and dispatched a vessel to Great Britain to demand an official explanation. Jefferson then consulted with his colleagues regarding potential military measures. But taking into consideration the pitiful state of the US Army and Navy, they agreed that they should first respond with economic pressure.
In 1807, the US government implemented the Embargo Act. This decree, which closed American ports to foreign trade and prevented US ships from leaving those ports, was extremely unpopular because it hurt America more than it did Britain or France. Two years later, Jefferson retired and left the foreign policy imbroglio to the new president, James Madison.
Jefferson had tried to stave off war, but when it came to pass in 1812, he supported it with a naive optimism. At the outset, Jefferson actually considered the conquest of Canada "a mere matter of marching." Even by the war's end, after the US had suffered dozens of defeats, Jefferson claimed that if it had lasted longer, the US would have taken Quebec and Halifax.
Jefferson, "the sage of Monticello", followed the course of the war very closely although he rarely volunteered his opinions to President Madison. He put great trust in his former Secretary of State, and he blamed Madison's subordinates for the American Army's blunders. Following the surrender of Detroit, Jefferson stated publicly that William Hull should be shot for cowardice and treachery.
One of Jefferson's most enduring legacies was the founding of the modern Library of Congress. When the British marched on Washington, they set fire to the Capitol and destroyed the original Library of Congress. Jefferson offered up his own library of almost 6,500 books to replace the lost volumes.