Most modern cruisers or destroyers aren't over 10,000 tons fully loaded, and are thus comparable to the light cruisers of WWII. The Dreadnoughts were a fair bit

Most modern cruisers or destroyers aren't over 10,000 tons fully loaded, and are thus comparable to the light cruisers of WWII. The Dreadnoughts were a fair bit bigger (2x at ~20,000 loaded), but indeed were not nearly as heavily armored as the WWII battleships of 30 years later. A loaded Iowa-class battleship displaced nearly 60,000 tons.