The Torchmen are a model of Clank designed by the Heterodyne family that comprises Mechanicsburg's air-defense system. They take the form of winged, generally humanoid figures equipped with glasses, a hat-like contraption, and a sword with a large sphere on the pommel that normally serves as the topmost lamp on the Torchman's lamp post perch. When activated they're enveloped in flame. (Compare their and forms.) They communicate with and are under the of the central Castle Heterodyne intelligence.
If you'd live to see the end of day,
from Mechanicsburg two leagues stay.
Two leagues is, in round numbers, about ten kilometers, although it varies considerably from region to region. 
In our last episode
In the comic proper, the Torchmen Agatha's passing the Heterodyne blood test administered by Castle Heterodyne. Having accepted Agatha's control, and very liberally interpreting her first orders, Castle Heterodyne enthusiastically deploys a swarming mass of Torchmen against the pink airship of Zola "Heterodyne" commanded by Baron Oublenmach and Duke Strinbeck. Strinbeck's order to ignore the Torchmen is not well by the airship's crew, who attempt to flee. During the chase, Castle Wulfenbach arrives and is attacked as well. Although Agatha is apparently unaware of the "two leagues" tradition, when she belatedly learns what is happening up there, she also non-lethally chasing the ships ten kilometers away. When both ships have left this radius, the Torchmen return to their posts, but not before carrying Von Pinn .following
The Print Novels
In Agatha H. and the Voice of the Castle, during the Torchman-launching scene, it is more explicitly noted that several of the constructs crash and burn without taking any fire from Castle Wulfenbach, due to lack of maintenance for many years following the disappearance of the Heterodyne Boys and the Wulfenbach empire rolling over Mechanicsburg.