Served as George Washington's aide de camp during the Revolutionary War. As Secretary of the Treasury, Hamilton was President Washington's closest political and military advisor. Hamilton advocated the establishment of a strong central government, a national bank and the formation of an American army. His frequent clashes with Thomas Jefferson over the most fundamental political questions led to the establishment of the two-party system in American politics. His vitriolic attack on Adams during the 1800 election may have cost Adams the presidency.