[PeterPrinciple]

http://www.guns.com/2013/07/03/save-the-navys-mark-7-16-inch50-caliber-cannons-big-sticks-speak-loudly-videos/

The largest battleship ever put to sea, the Japanese mega warships of the Yamato class, carried armor up to 26-inches thick. While no Iowa class battleship ever fought a Yamato, a section of 26-inch armor plate for these Japanese beasts was found at Kure Naval Base after World War 2. Settling a great historic ‘what if’, the plate was shipped to the US Naval Proving Ground in Dahlgren, Virginia and in tests, was shot at by a 16-inch/50cal armor-piercing round. The results? Zipped right through it like butter. To ensure bragging rights, the armor is on display at the US Navy Museum just in case anyone asked to see the math.

[wally_bert]

I had no idea.

Thank you.

[mountn man]

[iowamark]

26-inch thick armor from Japanese Yamato class battleship, pierced by a US Navy 16-inch gun firing a .50 caliber shell.

[tanknetter]

One more point about that Yamato plate: not that it was hit by a straight on shot.

The Yamatos, like other contemporary battleships, had their armor mounted at a downward-facing angle to increase protection. That test shot, in other words, was rigged - it never would have happened in a real battle hit.