The Ten Thousand. Portal Wars, #2

The Portals.  Ancient and mysterious, the constructs of a long-dead race, they allow instantaneous transit from one world to another, regardless of the distances involved.  When mankind discovered the first Portal on Earth it ushered in an age of exploration, as more and more distant worlds were explored and colonized.  But the dream turned quickly to a nightmare when mankind met the Tegeri.and plunged into half a century of desperate war. An older race than humanity, the Tegeri had found the Portals first.  Human settlements were attacked, their inhabitants massacred, and just like that, mankind was at war. But it was all a lie.  The Tegeri weren't hostile; they were waiting to greet mankind and share their technology and knowledge of the Portal network.  A cabal of Earth politicians started the war, seeking to use the fear of a bloodthirsty alien enemy to unite mankind under their totalitarian rule. After nearly half a century of bloody warfare, one man discovers the truth and swears to destroy the monstrous government that rules over Earth with an iron fist.