In the 17th century, a midshipman was a rating for an experienced seaman, and the word derives from the area aboard a ship, amidships, either where the original rating worked on the ship, or where he was berthed. Beginning in the 18th century, a commissioned officer candidate was rated as a midshipman, and the seaman rating began to slowly die out. By the Napoleonic era (1793–1815), a midshipman was an apprentice officer who had previously served at least three years as a volunteer, officer's servant or able seaman, and was roughly equivalent to a present-day petty officer in rank and responsibilities.