‘The Ice War’ (Asimovs Sept 2008) was set in 1720, and related the invasion of Earth by alien creatures, who come up against no less than Isaac Newton, Daniel Defoe and Jonathan Swift and one Jack Hobbes. A century later, with Napoleon’s troops on American soil, and invading England (in the history of these stories, Nelson has lost the Battle of Trafalgar).
Background to the aliens is provided as a descendant of Hobbes flees north with Rear Admiral Cuthbert Collingwood and his daughter, and one Miss Caroline Herschel, the army of Napoleon on their heels. The race is on to get launched the ship that will be used to challenge the aliens massing on Mars for an attack on Earth.
With the Duke of Wellington putting up a stout defense based around Hadrian’s Wall, the vessel, powered by anti-ice, is duly launched, it’s small crew heading off to make the ultimate sacrifice for the sake of humanity.
I have to own up to much preferring Baxter’s SF to his alternate history – oh for the XeeLee days!