By June of 1812, British conduct against American ships was intolerable. The British sought to block French trade across the globe as they fought Napoleon. As part of the attempt to block trade, British warships would stop American commercial ships to inspect their cargo. The main point was to prevent war materiel from reaching France. During these inspections, British naval officers would often forcibly take crew members from the American ships back to the British ships. Once onboard, these forcibly taken sailors would be required to serve on the ship, carrying out the duties of a sailor assigned to the ship in combat wherever the ship sailed. The process was known as impressment. President Madison was angered by the treatment of American crews.