Romney has recently revived the topic of the optimal size of the US navy as a political talking point, which has prompted some criticism from the left, who point out (justifiably) that the number of naval ships is not the best measure of strength, I came across this meme (above) posted by a friend, and this is what I had to say about it:
This is misleading because the bottom picture of the USS North Carolina was decomissioned in 1947. What you see here in 2012 is actually a war museum.
Moreover, it is misleading because the USS North Carolina, along with her sister ships in the Iowa class battleships never actually engaged any enemy ships even though they were deployed in the active pacific theater of WWII. The reason is that the whole concept of heavily armored big-gunned battleship turned out to be utterly useless in the aircraft age. The German battleship Bismark was one of the most powerful battleships ever built, yet it was crippled by a lonely biplane armed only with a single torpedo, launched from a wooden-deck converted aircraft carrier sitting well out of range of the Bismark's 15-inch cannons.
Because they proved so useless during the world war, the US navy has not launched any new battleships since 1944, and with the exception of brief coastal bombardment operations in Korea, Vietnam, and Operation Desert storm, all of the US battleships have been confined to the navy's off-duty "mothball fleet" since the world war. The last US battleship--the USS Missouri--was finally scrapped (actually, converted to a museum) in 1992. She was the last battleship to exist in any navy anywhere in the world.
In modern navies, guided missile destroyers have entirely replaced the function that battleships were originally designed to fill. Guided missiles can easily out-range even the best of the old conventional cannons, are far, far more accurate, and far more destructive than even the highest caliper cannons. Unlike battleships, which could slug out volleys back and fourth all day without actually sinking anything, modern guided missiles are much closer to a one-shot sink technology: any missile that makes it through the enemy ship's close-in weapons shield will almost certainly sink the ship.
However, even with guided missile destroyers, surface-to-surface naval warfare is incredibly unlikely. By far the easiest way to sink any enemy ship or submarine is with an aircraft, so almost all of the actual fighting that the US navy does is conducted by aircraft carriers. So while destroyers do have ample surface-to-surface capabilities, their primary function is to protect the carriers from submarine attacks by deploying depth charges and torpedoes, and enemy aircraft by deploying surface-to-air missiles. All of the other combat ships used by the navy, such as frigates are organized around protecting the core battle group of each fleet, consisting of an aircraft carrier and four destroyers. They provide the same capabilities as the destroyers--anti-sub, anti-aircraft, anti-mine operations, from a smaller and more maneuverable platform.
My point here is that US naval power is derived entirely from the number and strength of its aircraft carriers. The only reason to ever build a naval ship other than an aircraft carrier is to protect the aircraft carriers we already have.
