In the days of fighting sail, the largest kind of warship, the “ship of the line” was the main battleship of its time. It was almost a 100 yards in length and could carry as much as a 100 guns, with a crew of about 800. They operated in big fleets, and were designed to engage other ships of the line in formal tactical array. Ships of the line were roughly comparable to modern battleships, although modern navies no longer have any battleships in their inventories. Too expensive, too vulnerable to aircraft and submarines.

The smallest warships were corvettes, or sloops, used primarily as scouts or pickets, or to carry dispatches. They were armed, but not expected to engage enemy ships, except those of their own size. They were roughly comparable to a modern destroyer.

Intermediate between the two were frigates. Frigates could act as escorts to other vessels, either larger or smaller, do blockade duty, or as independent cruisers and raiders. Unlike the cumbersome ships of the line, or the tiny corvettes, frigates were all-purpose ships whose captains prided themselves on being able to conduct complex maneuver ballets and tacking duels against vessels similar to their own in size and armament. Most one-on-one actions were between evenly-matched frigates. The sailing frigate was roughly comparable to a modern cruiser.

My own ship was originally classified as a DLG, a Guided Missile Destroyer Leader. Although it was called a frigate in our Navy the terminology was eventually discouraged since NATO used the term for ships smaller than a destroyer, but bigger than a corvette. Eventually, after I left the Dewey,
the Navy reclassified her as a DDG, or Guided Missile Destroyer.

Today, most surface combatants are destroyers, (DD), a ship class roughly in the size and class of a large frigate. America is abandoning most of its ship classes, and replacing them with destroyers, all-purpose ships capable of air defense, anti submarine warfare, shore bombardment, or surface action. The modern destroyer is much more capable, and much larger, than its WWII counterpart. In fact, modern destroyers are comparable to WWII cruisers. Most modern navies are phasing out the cruiser and going to a one-size-does-all class, the modern destroyers.

So for a general description of modern naval surface combatants, the following hierarchy exists, with some variation from country to country:

patrol
corvette
frigate
destroyer
cruiser

In fact, the term destroyer itself is misleading. Around the late 19th century, the invention of the torpedo, delivered by the new, fast Torpedo Boats, meant that the large, expensive battleships and cruisers were now vulnerable to attack by swarms of small, fast, cheap and expendable torpedo boats. A new class of ship, the Torpedo Boat Destroyer, evolved to meet this new threat. It was designed to protect bigger ships from attack by smaller ones, and eventually, other duties such as convoy escort, anti-sub and anti-aircraft were added on to their missions. The term ‘destroyer’ stuck, although it is somewhat of an anachronism.

It was a larger, ocean going vessel and the current trend is for most navies to rely primarily on destroyers as all-purpose ships. Corvettes, Frigates, and Cruisers are still in service, but they are being allowed to age gracefully into obsolescence, replaced by very big, very large, very expensive destroyers. There hasn’t been a big naval war in a long time. When there finally is one, the Admirals will realize they had totally misjudged how it would play out and they went out to fight with the wrong mix of ships. It happens every time.