The Imperial Navy's Invincible-class Fast Battleship was the brainchild of Admiral Kisher. Segmentum Tempestus suffers from Heretic raiders constantly sliding from the empty space between its far-flung star systems to attack Imperial worlds. In particular, large Chaos and Eldar raiding ships were often faster than the Escort flotillas of Battlefleet Tempestus. Kisher dreamed of a starship class that was as fast as a Light Cruiser but possessed the firepower of a Battleship. Such a ship, he reasoned, would be capable of swiftly hunting down Heretic raiders and then dispatching them equally swiftly with massed long-range firepower. He pressured the Fleet Tech-magi until, much against their will, they conceived and developed the first Fast Battleship class. The Tech-magi protested in vain that severe compromises were inherent in the class' internal compartmentalisation and back-up redundancy in vital systems, especially the power distribution grid. Kisher brushed aside such pessimism, claiming that the Fast Battleships would be faster than starships that were stronger and stronger than starships that were faster. Up to a point this theory proved true and the Fast Battleships won a series of ship-to-ship actions with Heretic and xenos Cruisers.
However, the problem soon emerged that because Fast Battleships were as large as actual Battleships, armed like Battleships and looked like Battleships, Imperial Navy tacticians were tempted to use them as Battleships. In the battle line they proved horribly vulnerable; Fast Battleships proved capable of dishing it out but not take it. They were like heavyweight boxers with glass jaws. Fast Battleships soon proved unpopular with fleet officers and were christened, with traditional naval black humour, as "Kisher's Kombustibles." Fifteen starships of the class were ordered but only ten were produced after three exploded in fast succession at the Battle of Swetz Climb.
- Battlefleet Gothic Magazine 13