Ships of the line were 1st, 2nd, or 3rd-rated ships in the rating system of the Royal Navy.

In the age of sail, after the development of the line of battle tactic in the mid 17th century, and up to the mid 19th century, a ship of the line (of battle) was a warship powerful enough to take a place in the battle line. (Another term, a "line of battle" ship, shortened to become a "battleship", but this is a later usage and is not appropriate for the age of sail.)

The fact that a ship would have to stand and fight its opposite number in the enemy line, whatever the size of the enemy ship, put a lower limit on the size of vessel which could be allowed into the line. Generally, this meant a third-rate or larger ship, with guns on two or three (or in rare cases, four) decks. Before 1700 the minimum size for a ship of the line would be around 50 guns, steadily climbing to 74 during the late Napoleonic period. European navies in particular used battleships to fight fleet actions which might last for days and involve over 100 ships.

Ships too small to stand in the line were used for convoy escorts, scouting, patrolling, raiding, blockading and as flagships on foreign stations, with the frigates, which mostly carried all their guns on a single deck, as the most successful all-round design for those purposes.

In fiction

Isaac Asimov adapted the term "ship of the line" to apply to the armed spaceships which served a similar role to the old naval vessels for the Galactic Empire of his Foundation trilogy, as mainstays of the space fleet.

In a similar vein is David Weber's use of the term "ship of the wall".

External links

• Ship of the Line from battleships-cruisers.co.uk - History of the Ship of the Line of the Royal Navy from the galleons of 1650 to the First Rate 120 gun Ship of the Line of 1845, including Caledonia Class, Queen Charlotte, Trafalgar, Victory, Leviathan, Royal Sovereign, Vengeur and Black Prince Class. - ship listing, historic information, pictures