That voice!
Due to the secretive nature of the order of the Knights of Jove, not much can be definitively determined about these enormous manned exosuits ✣ . Whoever is responsible for their original creation, they are lavishly ornamented in the style of traditional white chessmen, with golden headgear indicating the class. Each exosuit seems to be piloted by a person, although whether these pilots are, in fact, members of the Knights of Jove has not been revealed.
These machines first appear ✣ at the Siege of Mechanicsburg, where they arrive just in time to interrupt Franz in the process of killing the dragon he calls Pretty Boy, and then proceed to showily announce their intention to "protect" Agatha from the attacking Wulfenbach forces in the name of the Storm King. (It should be noted that this is essentially the intended plan detailed ✣ by Zola Malfeazium when she is still attempting to establish herself as the new Heterodyne.) Baron Klaus Wulfenbach considers them to be "the real players" in the game, prompting him to finally reveal the true extent of the forces he has assembled to attack the city.
Their operators appear to be a different faction from a previous group of attackers piloting war stompers, led by Rudolf Selnikov and also claiming to be the Knights of Jove before being destroyed ✣ by Gilgamesh Wulfenbach.
The "king" of the set is manned by self-proclaimed Storm King Martellus von Blitzengaard, a cousin of Tarvek Sturmvoraus. The craft is destroyed ✣ when its pilot "Tweedle" attempts to squash one of the Dreen, though Tweedle is able to jump to safety.
The Knights appear to have been launched ✣ from The Refuge of Storms.
It is not shown if any of the remaining Knights survive the Siege, but following the Timeskip one of them, or another ✣ of the same class, is used to successfully extract a wounded Martellus after he engages Gil in combat near the Refuge, although according to its harried pilot, the vehicle is critically damaged by Bohrlaikha in the process.
The Novels[]
Their appearance in Agatha H. and the Siege of Mechanicsburg pretty much follows the comic version, although it's made clearer that at least some of them get destroyed by Wulfenbach forces.