Uller Uprising by H. Beam Piper — Read

The company fleet hung off Keegark, at fifteen thousand feet, in a belt of calm air just below the seesawing currents from the warming Antarctic and the cooling deserts of the Arctic. There was the _Procyon_, from the bridge of which von Schlichten watched the movements of the other ships and airboats and the distant horizon. The _Aldebaran_ was ten miles off, to the west, her metal sheathing glinting in the red light of the evening sun. There was the _Northern Star_, down from Skilk, a smaller and more distant twinkle of reflected light to the north of _Aldebaran_. The _Northern Lights_ was off to the east, and between her and _Procyon_ was a fifth ship; turning the arm-mounted binoculars around, he could just make out, on her bow, the figurehead bust of a man in an ancient tophat and a fringe of chin-beard. She was the _Oom Paul Kruger_, captured by the _Procyon_ after a chase across the mountains northeast of Keegark the day before.

And, remote from the other ships, to the south, a tiny speck of blue-gray, almost invisible against the sky, and a smaller twinkle of reflected sunlight -- a garbage-scow, unflatteringly but somewhat aptly rechristened _Hildegarde Hernandez_, which had been altered as a bomb-carrier, and the gun-cutter _Elmoran_. With the glasses, he could see a bulky cylinder being handled off the scow and loaded onto the improvised bomb-catapult on the _Elmoran_'s stern. Shortly thereafter, the gun-cutter broke loose from the tender and began to approach the fleet.