Other causes of dispute arose from the determination of the British government to exclude the Americans from the blockaded ports of France, and from that inexhaustible source of quarrel, the impressment of British seamen from American vessels, especially as the difficulty of distinguishing British from American seamen led occasionally to the impressment of American native born citizens.

In June, 1807, occurred the rencontre between his majesty's ship Leopard and the Chesapeake, which terminated in the forcible extraction from the American frigate of four deserters from British ships of war.

The British government instantly disavowed this act, and recalled Vice-Admiral Berkeley, who had given the order to search the Chesapeake.

Jefferson, however, not only issued a proclamation interdicting all British ships of war from entering the ports of the United States, but proposed to congress to lay an embargo on American vessels, and to compel the trading ships of every other nation to quit the American harbours.

This proposition was warmly opposed by the federalists, or Washingtonians, but it was nevertheless adopted by large majorities.