In 1806, at the age of seventeen, Cooper joined the crew of the merchant ship Sterling as a common sailor. At the time, the Sterling was commanded by the young John Johnston from Maine where Cooper served as a common seaman before the mast. His first voyage, taking some forty stormy days at sea, brought him to an English market in Cowes with a cargo of flour. There Cooper saw his first glimpses of England. After passing through the Strait of Dover and arriving at Cowes, the Sterling dropped anchor. Because Britain was in the midst of war with Napoleon's France at the time, their ship was immediately approached by a British man-of-war and was boarded by some of its crew. They seized one of the Sterling's best crew members and impressed him into the British Royal Navy.