Book 1

Worldwar: In the Balance

by Harry Turtledove

Published 3 November 1994
World War II seethes across the planet. Hostilities spread in ever-widening circles of destruction: Nazi Germany, Soviet Russia, Britain, France, Japan, Italy Africa - the fate of the world hung in the balance. Then the real enemy arrives. Out of the skies comes an invasion force the like of which Earth has never known - and worldwar is truly joined. The invaders are inhuman and they are unstoppable. Their weaponry is overwhelming and their goal is simple: Fleetlord Atvar has arrived to claim Earth for the Empire. 'The wizard of If.' Chicago Sun-Times 'The standard-bearer for alternate history.' USA Today

Book 3

Alien invaders from another star system have attacked the Earth, wreaking massive destruction and havoc with their terrifyingly advanced military technology. Humans are forced to unearth secret caches of terrible, once-forbidden weapons. Hitherto unthinkable tactics are brought into action against the alien enemy.
Even as fuel shortages force people back to the horse and cart, the world's scientists work desperately to create Earth's first atom bombs - with horrific results. If the carnage and slaughter ever stop, will their be any pices to pick up?

'The wizard of If.' Chicago Sun-Times
'The standard-bearer for alternate history.' USA Today