Impressment is the act of kidnapping people to serve as sailors. It was much used by the Royal Navy during the 18th century and early 19th century as a means of crewing warships. The Royal Navy impressed many British and American sailors during the late 1700s and the early 1800s.
Conditions in the Royal Navy were very bad and the pay was not very much. So many British sailors decided to desert from the Royal Navy and join American merchant ships because the pay and the conditions were much better. As a result the Royal Navy started stopping American merchants and looking for British deserters. Since it was difficult to tell whether a sailor was British or American, the Royal Navy impressed over 6000 American sailors during the early 1800s. This was one of the many factors leading to the War of 1812 in North America.