The British ship fired upon the off the Virginia coast in June 1807, and Jefferson prepared for war. He issued a proclamation banning armed British ships from U.S. waters. He presumed unilateral authority to call on the states to prepare 100,000 militia and ordered the purchase of arms, ammunition, and supplies, writing, "The laws of necessity, of self-preservation, of saving our country when in danger, are of higher obligation strict observance of written laws". The was dispatched to demand an explanation from the British government; it also was fired upon. Jefferson called for a special session of Congress in October to enact an embargo or alternatively to consider war.