The UEF Bismarck is the most powerful ship in the UEF navy.This unit is not included neither in the original game, nor in Forged Alliance, but is added through a mod (likely BlackOps).
It is a unit that is added in the mod BlackOps and is not available in the stock game. It can be found here: http://supremecommander.filefront.com/file/Blackops_Unleashed_Unit_pack;95539
The main weapons of this ship are the four cannons that when hitting their target result in a small thermonuclear explosion.
The secondary weapons consist of about six smaller ship to ship/close quarters weapons, a few torpedo tubes, anti aircraft guns and some other things.
It's a command ship and although VERY powerful on it's own, it should be escorted with at least 4 Battlecruisers, 10 Tigersharks and 15-20 cruisers/destroyers for a powerful mix.
The name by now has been changed to Conquest Class.
See http://forums.gaspowered.com/viewtopic.php?f=7&t=31172 for current mod version and download.
New weapon systems consist of 3 Z-dubbed extreme range antimatter cannons that upon impact give the term "overkill" an entirely new meaning, as well as 12 double barreled deck guns that deal swiftly with anything foolish enough to approach on the water surface.
At 81000 HP and a reasonable traveling speed it requires a significant naval force to be stopped. Especially as you preferably want to sink it before it bombs your base back to the stone age.