A Klingon mobile battle base was an offensive military vessel designed by the Klingon Empire in the late 23rd century. Intended to support Klingon expansion into new territories without the need for ground-based outposts, the mobile base measured 3050 meters long, with a mass of 30 million metric tonnes. It was able to travel at Warp 5, could carry thirty Birds-of-Prey, and was armed with fifty double-barreled phaser banks.
In January 2284, a Klingon mobile battle base was located and destroyed by operatives of Starfleet Intelligence inside Federation space, near the region of Starbase 21. (FASA RPG module: Star Trek IV Sourcebook Update)
The first of a planned dozen mobile battle bases was constructed in 2291, though it was only minimally functional, owing to the internal economic problems of the Empire. That year, the prototype battle base was commandeered by Vykul Marto, leader of the Torye faction of the Payav, in a ploy to overthrow the government of planet Mestiko. The battle base and its hijackers were destroyed by a subspace tear created by a subspace-disruption weapon the Torye had stolen from the Discovery Center on Varnex. (TOS - Mere Anarchy eBook: The Blood-Dimmed Tide)