Expeditionary Force

The aliens who saved Earth are the same ones itching to strip-mine it, and the only thing between humanity and the scrap heap is a jumpy Army grunt and a talking beer can. That, more or less, is the pitch of Craig Alanson's Expeditionary Force: near-future military science fiction in which Earth stumbles into a galactic food chain it was never built to survive. Sergeant-turned-Colonel Joe Bishop keeps the planet breathing mostly by luck, nerve, and the grudging genius of Skippy the Magnificent, an ancient, godlike, monstrously arrogant artificial intelligence shaped like a can of beer and firmly convinced that all humans are filthy monkeys. The main sequence runs long, from Columbus Day across more than a dozen novels, trailing Joe's self-styled "Merry Band of Pirates" as they steal a derelict starship, bluff civilizations a million years ahead of them, and lurch from one save-the-world scramble to the next while keeping Earth off everybody's radar. The Mavericks branch widens the war to soldiers stranded elsewhere in the same galaxy. What carries it is the banter. Every suicidal plan gets argued to death between an ego the size of a galaxy and a man who mostly wants a sandwich, and the stakes stay real even when the tone refuses to. Start at Columbus Day and read in publication order; the gags and the war both compound.