Why is a Frigate a Frigate (and not a Destroyer or a Corvette)

Why is a frigate a frigate? Looking at these models, can you tell which ones are the frigates, which ones destroyers, and which ones cruisers? It is confusing. This video can help you with that. Let me tell you how the designation frigate came about. You will then probably understand a lot better why some ships are considered frigates, while similar looking ships are corvettes, Just before World War II, there were no frigates. The name had come about during the age of sail. Frigates were then square-rigged, three-masted, fast sailing ships with only one gun deck. This distinguished them from ships at the core of the 18th century battle fleet. The line of battle was made up of ships of the line. Their function was to release maximum firepower on the enemy line of battle. So they ideally carried as many heavy guns as you could fit into a ship and still sail. It required them to have multiple gun decks. Frigates, on the other hand, were built to be a balance between speed, armament, and seakeeping ability, with an emphasis on speed. They would often be sent on scouting missions, to carry messages, to protect the sea lanes, or even to attack enemy trade vessels. Pretty much the way it is portrayed in the movie Master and Commander. There were even frigates present at the Battle of Trafalgar. Although they were outside the battle lines, they served to relay messages from the flagship to ships who couldn't see the signals from the flagship. By the way, even though the Franco-Spanish fleet was defeated at Trafalgar, every single French frigate managed to escape, making good use of their speed. So the frigate was smaller, lighter, and faster than the ship of the line. But it was heavier and larger than the next straight down, the corvette. The sailing corvette resembled a scaled-down frigate. She was also a swift sailor, but with lesser accommodation and lighter armament. Therefore, corvettes were less suited to spend long periods at sea, withstand heavy weather, and travel great distances. Basically, the corvette was the smallest type of fully ship-rigged warship. As warships were fitted with steam engines in the 19th century, everything changed for the frigates and the corvettes. Frigates and corvettes could no longer be sure to outrun more powerful ships. Gradually, they disappeared. By the 1890s, there were no more frigates and corvettes in the world's naval fleets. Just before World War II, ship categories were well defined. The heavyweights were the battleships. Battleships were all about the firepower of their large-caliber guns. These guns were large enough for a man to crawl through the gun barrel, and fired grenades, which weighed as much as a small family car, over distances of up to 20 miles or 30 kilometers. They were protected against enemy grenades by heavy armor. The battleship was the modern equivalent of the line. Smaller and lighter than the battleships were the cruisers. They often looked very similar to battleships. If you'd spot one at sea, with no battleship nearby, you could be forgiven to think that you were looking at a battleship. While battleship displacement was typically around 35,000 to 45,000 tons, cruisers were by treaty not allowed to exceed 10,000 tons. Their guns were limited to either a 6-inch caliber for light cruisers, or an 8-inch caliber for heavy cruisers. The prefix light or heavy refers to the size of the cruiser's guns, not to the displacement of the ship. Cruiser armor wasn't as heavy as battleship armor. A cruiser wasn't supposed to fight battleships. But an engagement between cruisers, like the Battle of the Java Sea or the Battle of the River Plate, would be fought much the same way as a battle between battleships. Cruisers were typically considerably faster than battleships. Yet they were still well-armed, sizable ships with good accommodation and good endurance, capable of covering great distances and operating independently for extended periods. In that respect, they were WWII's equivalent of the frigates from the Age of Sail. The next smaller fighting ships were the destroyers. Originally called torpedo boat destroyers, they had developed into a versatile and invaluable part of the surface fleet. The need for destroyers had arisen at the end of the 19th century, when the self-propelled explosive torpedo had become a serious threat to large warships. The torpedo could be launched from small maneuverable fast ships and disable or even sink the mighty battleships and cruisers. Torpedo boat destroyers proved to be an effective countermeasure. Employed in a protective screen around larger valuable ships, they could fend off attacks by the smaller ships. Therefore, they were typically very fast and armed with quick-firing guns to effectively destroy approaching torpedo boats. Unlike battleships and cruisers, destroyers were not armored, as armor would slow them down and diminish their hunting capacity. It was simply accepted that destroyer crews would go in harm's way without the protection of armor. It was realized that the small torpedo boats, the original threat to the battleships, were too small to be effective in heavy seas and lacked the endurance to effectively follow a fleet on the high seas. However, it was practical to arm the destroyers with torpedo batteries. These destroyers could be sent towards enemy ships to conduct torpedo attacks. As such, destroyers had effectively become the threat they were originally supposed to counter. No task force could do without them. As they were ever-present, it was the destroyers who were constantly adapted to counter new threats to the capital ships they were to accompany. As submarines became effective warships, destroyers were fitted with submarine detection equipment and depth charges to hunt and destroy enemy submarines. The first destroyers were of relatively modest displacement, around 500 tons. But destroyer tonnage soon exceeded 1,000 tons, as they were fitted with more equipment and weapons. By the beginning of World War II, destroyer tonnage was on average around 1,200 tons, although new powerful classes in some navies approached 2,000 tons. These large powerful destroyers were considered by many experts a conceptual mistake. Being too large and expensive, they couldn't be built in the large numbers you'd like to see for destroyer flotilla maneuvers. It was considered better to build more numerous, smaller, slightly less powerful units. Destroyers weren't yet supposed to become small cruisers. An example of powerful destroyers was the British Tribal class. They were rather heavily armed with surface guns to counter enemy destroyers, and had considerable anti-aircraft weapons. But their torpedo armament was reduced to just one battery of four torpedoes. As such, some considered the tribals as warships of a different category. Reminiscent of 18th century categories, it was considered to classify the fast and powerful tribals as corvettes. This would have made sense, but never actually happened. But now we finally get to the point with this little ship. As destroyers had become too valuable in their offensive and defensive duties for the surface fleet, it was undesirable to use them as escorts for relatively slow, mercantile ships, which needed to be protected from submarine attacks. Specifically for that purpose, the British Royal Navy had this ship developed. The Flower class was a modest, uncomplicated ship with submarine detection equipment, depth charges, and a modest gun. She'd be expected to detect, fend off, and fight submarines below and at the surface. But she was no match against enemy destroyers or other powerful units. Strangely enough, the British Admiralty chose to categorize them as corvettes. This was a bit ridiculous as the corvettes from the age of sail were fast ships and still a good fighting match against many other sailing warships. Besides, there had already been modest speed escort-type ships in service since World War I, and they had been categorized as escort sloops. Many of these earlier escort sloops were larger, faster, and more powerful than the Flower class. As World War II progressed, the Flowers often escorted convoys all the way across oceans. Because German submarines proved to have sufficient range to attack far away from their home bases. Although the Flowers were capable of doing this work, they had originally been designed for surface closer to home. For this ocean work, they were really a bit under-dimensioned. Besides, early war experience showed they could do with more powerful machinery, detection equipment, and armament. A larger type of ship was soon developed in the River class. These ships were an improvement in ASW capabilities and better equipped to defend against attacking aircraft. Initially, they were to be considered twin-screw corvettes. But supposedly, Royal Canadian Navy Admiral Nels proposed to categorize these new ships as frigates. This was done. And there we are. Building on the questionable decision to categorize the Flowers as corvettes, there was now a class of medium-speed, moderate-displacement, moderately armed escort ships, which were called frigates. What would Jack Aubrey have thought about that? These new frigates were not fast, independent fighting ships. They would have been better categorized as escort sloops. It doesn't surprise me that not everybody agreed with these new category designations. In fact, when American shipyards started building escort ships for the British Royal Navy, these ships were commissioned as captain class frigates in the Royal Navy, while the very same ships would serve as destroyer escorts in the US Navy. The US Navy considered such ships as destroyers of the escort type, as opposed to destroyers of the fleet destroyer type. The US Navy also had a few British Flower class corvettes on loan and had categorized them as patrol gunboats, not as corvettes. There were no frigates or corvettes in the US Navy. But the Royal Navy did categorize such escort ships as frigates, and the category continued to diversify frigates into subcategories. Radar picket frigates were supposed to provide early warning against attacking aircraft. Air defense and air direction frigates were supposed to provide guidance for friendly aircraft and provide air defense for the protected ships. ASW frigates had the traditional role of protecting the escorted ships against enemy submarines. And general purpose frigates were designed to do a bit of everything. Following World War II, not many navies had the budget or the desire to maintain a large fleet of corvettes, frigates, destroyers, cruisers and battleships. For most navies there was just a need for a ship that could do a little bit of everything. The logical choice for many navies was the frigate. The categories were clear. Battleships and cruisers are obvious. Destroyers would be the smaller fast maneuverable fighting ships to be used in fleet operations. The frigates would be the smaller slower fighting ships with a more defensive orientation. But then there was another development which increases the confusion. The German Type 21 U-boat. Whereas earlier U-boats would achieve underwater speeds of around 5 to 7 knots, the Type 21 could attain underwater speeds of up to 17 knots. Both the Russian Navy and the US Navy further developed this technology after World War II. This meant that the frigates, most of which had a maximum speed of around 20 knots, would have a very difficult time chasing and fighting such submarines. There was nothing for it. Frigates had to increase their speed. And this really blurred the distinction between frigates and destroyers. New types of frigates were getting larger and could now also attain speeds which would allow them to keep up with fleet task forces. If you're not a naval analyst you may be hard-pressed when you see ships of approximately the same size with similar looking armament capable of comparable speeds to decide whether you should call it a frigate or a destroyer. But roughly you could say that the world's frigates were a bit slower and smaller than the But then something strange. When you open up a 1958 copy of Janes you'll see that a lot of countries will have frigates, mostly in the displacement range between 1,000 and 2,000 tons. However, at that time the United States Navy is about to launch some ships in the 5,000 ton range which are rated as frigates. These are very different ships. This was to be the Farragut class. Large, fast, well-armed fleet escorts. And they were entering the fleet at a time when the largest new British frigates were the 2,200 ton Whitby class anti-submarine frigates. These large American frigates were more akin to missile-armed light cruisers in other navies. As fighting units they were more in line with the frigates from the age of sail. Fast, sizable, well-armed ships. In that respect it made sense to call them frigates. Smaller ships, comparable in size and armament to the 1958 British frigates, were still rated as destroyer escorts in the US Navy. But the US Navy was pretty much the only navy doing that. It was more a matter of naval tradition that the US Navy chose to categorize these larger ships as frigates. But this changed in 1975. This article from the Navy Times of December 1974 announces the change. More in line with the rest of the world, the US Navy decided to redesignate 200 ships. Apparently to end some confusion. I'm not so sure that it worked. Initially the larger US guided missile frigates were redesignated as guided missile cruisers. But eventually the Farraguts would be redesignated as destroyers. You see, destroyers had been increasing in size since World War II and were now often of a size and displacement previously associated with light cruisers. Notable was the British County class. Large guided missile destroyers about twice the size of any other British destroyers. The main reason for categorizing them as destroyers was because it was thought that this would make it easier to get their funding approved. It would have been more realistic to designate them as guided missile cruisers. But destroyers they were and destroyers they remained. Since then it seems to have gotten more confusing. As a rough general rule you could say that post-World War II cruisers are the larger fleet combat ships. Destroyers are large these days but smaller than cruisers and typically still associated with fleet combat duties. Frigates are a bit smaller yet and marginally slower than destroyers. Frigates will often be ships with anti-submarine, anti-aircraft, aircraft direction or general purpose capabilities. Corvettes are nowadays the smaller fast ships intended for literal use. But as soon as you try to define the boundaries between these categories you'll run into trouble. Set a boundary and you will immediately have to explain many exceptions. The categories simply won't make sense until you accept that there is no definite yardstick. One man's destroyer is another man's frigate. When you look at the trunk class ships of the Royal Netherlands Navy during NATO exercises often compared to TV detective Kojak I wonder why. You may find that they were considered destroyers, frigates or cruisers depending on which source you look at. Janes considered them destroyers based on their size and capabilities but the Dutch themselves considered them frigates based on naval tradition and their anti-submarine role in NATO. Besides it's hard these days to quickly judge the fighting potential of many warships. Much more than World War II ships they have become platforms for guided weapons whose capabilities are not readily obvious. To me speculations like these by people who should know better betray a lack of understanding of how these categories came about and their true significance. It's looking for exact values where none exist. Frigates are not a historically justified designation carried forward into a modern analogy. The modern designation frigate is based on a misguided 1942 decision. Only through circumstance can modern frigates claim a role which would vaguely be compared to the role of sailing frigates which are not their ancestors. A frigate is a frigate because the owner chooses to call it a frigate. In my opinion this anecdote says it all. Some years ago the South African navy was about to commission new ships. In the discussions that followed a navy official remarked well we're not talking about frigates we're only talking about corvettes and a journalist remarked corvette or frigate it's still a warship.