Worldwar: In the Balance

Worldwar: In the Balance is a 1994 alternate history novel by American writer Harry Turtledove. It is the first novel of the Worldwar tetralogy, as well as the first installment in the extended Worldwar series that includes the Colonization trilogy and the novel Homeward Bound. The plot begins in late 1941, while the Earth is torn apart by World War II. An alien fleet arrives to conquer the planet, forcing the warring nations to make uneasy alliances against the invaders. Meanwhile, the aliens, who refer to themselves as the Race, discover that their enemy is far fiercer and more technologically advanced than expected.