Capital ship

The capital ships of a navy are its most important warships; they are generally the larger ships when compared to other warships in their respective fleet. A capital ship is generally a leading or a primary ship in a naval fleet. There is usually no formal criterion for the classification, but it is a useful concept in naval strategy; for example, it permits comparisons between relative naval strengths in a theatre of operations without the need for considering specific details of tonnage or gun diameters. A notable example of this is the Mahanian doctrine, which was applied in the planning of the defence of Singapore in World War II, where the Royal Navy had to decide the allocation of its battleships and battlecruisers between the Atlantic and Pacific theatres. The Mahanian doctrine was also applied by the Imperial Japanese Navy, leading to its preventive move to attack Pearl Harbor and the battleships of the U.S. Pacific Fleet. The naval nature of the Pacific Theater of Operations, more commonly referred to as the Pacific War, necessitated the United States Navy mostly deploying its battleships and aircraft carriers in the Pacific. The war in Europe was primarily a land war; consequently, Germany's surface fleet was small, and the escort ships used in the Battle of the Atlantic were mostly destroyers and destroyer escorts to counter the U-boat threat. Before the advent of the all-steel navy in the late 19th century, a capital ship during the Age of Sail was generally understood as a ship that conformed to the Royal Navy's rating system of a ship of the line as being of the first, second, third or fourth rates: First rate: 100 or more guns, typically carried on three or four decks. Four-deckers suffered in rough seas, and the lowest deck could seldom fire except in calm conditions . Second rate: 90–98 guns. Third rate: 64 to 80 guns (although 64-gun third-raters were small and not very numerous in any era). Fourth rate: 46 to 60 guns.