The U.S. Navy is designing a new destroyer, and it's as big as a battleship, at least a battleship of a century ago, The new design, the DD(X), is to displace 14,000 tons, be 600 feet long and 79 feet wide. A crew of 150 sailors will operate a variety of weapons, including two 155mm guns, two 40mm automatic cannon for close in defense, 80 Vertical Launch Tubes (containing either anti-ship, cruise or anti-aircraft missiles), six torpedo tubes, a helicopter and three helicopter UAVs.
A century ago, a Mississippi class battleship displaced 14,400 tons, was 382 feet long and 77 feet wide. A crew of 800 operated a variety of weapons, including four 12 inch, eight 8 inch, eight 7 inch twelve 3 inch, twelve 47mm and four 37mm guns, plus four 7.62mm machine-guns. There were also four torpedo tubes. The Mississippi had a top speed of 31 kilometers an hour, versus 54 for DD(X). But the Mississippi had one thing DD(X) lacked, armor. Along the side there was a belt of 9 inch armor, and the main turrets had 12 inch thick armor. The Mississippi had radio, but the DD(X) has radio, GPS, sonar, radar and electronic warfare equipment.
The DD(X) would make quick work of the Mississippi, spotting the slower battleship by radar or helicopter, and dispatching her with a few missiles. The Mississippi's 12 inch guns had a maximum range of 18 kilometers, versus 130 kilometers for the Harpoon anti-ship missile. There has always been some debate if modern anti-ship missiles could really take down a battleship, what with all that armor and plenty of sailors for damage control work. Well never know, as the Mississippi ended its career in the Greek navy, and was sunk by German aircraft in 1941.
The designation "destroyer" has actually gone out of favor in most nations. Part of this is political correctness. Ships that for a century had been called "destroyers" are now usually called "frigates." Most American "destroyers" for the last few decades would be classified as "cruisers" for most of the last century. The proposed DD(X) is a hundred feet longer and 20 feet wider than the current Arleigh Burke class destroyers. And with 50 percent greater displacement. Moreover, the DD(X) will have half the crew of the Arleigh Burkes. This will mean a lot more comfortable living conditions for the crew. This marks another major difference from 14,000 ton ships of a century ago. The Mississippi had most of the sailors sleeping in hammocks, tying them up during the day so there was room to sit down and eat. The Mississippi also had trough type urinals and unwalled johns in the heads, and salt water showers. Sailors spent a lot of time cleaning the ship, including scrubbing the deck and polishing and painting. The DD(X) accommodations will be more like what you would find in a cruise ship, and the DD(X) will be built for low maintenance (including a stainless steel hull.)
Another major difference is the shift from guns to missiles as the primary weapon. The DD(X) has four guns, the Mississippi had 48. But the Mississippi represented another milestone, it was the last of the "pre-Dreadnought" battleships. Warship designers in Britain and the United States had concluded that technology (longer range guns and better fire control) made it obvious that the next generation of battleships should put most of their firepower into the maximum number of the largest guns a ship could carry. While the British put their Dreadnought battleship into commission first (1906), the American USS Michigan, an 18,000 ton ship, was the first to be laid down. With eight 12 inch guns and a top speed of 33 kilometers an hour, this type of battleship was the most powerful thing afloat until World War II, when aircraft carriers made battleships obsolete.
The DD(X) is still "pre" whatever the next dominant type of warship will be. But it's ironic that a hundred years later, the descendent of the 14,000 ton Mississippi is a 14,000 ton surface ship that has more firepower, a longer reach and the ability to see targets hundreds of kilometers away, and is called a destroyer. And what kind of destroyers escorted the Mississippi? They were ships of under a thousand tons displacement, with crews of about a hundred sailors. Armed with a few 3 inch guns and some torpedoes, no one at the time expected them to evolve into a 14,000 ton warship.