The Peshawar Lancers by S.M. Stirling
A fine example of the alternate history sub-genre of Science Fiction. The change in history occurred in 1878, when a series of asteroid strikes caused a “nuclear winter” effect. As a new Ice Age quickly over ran Europe, the British Empire relocated their seat of power to Imperial India. It’s a “rousing good adventure”, complete with Airships and large, steam powered mechanical Difference Engine type computing devices.