Battle Earth: Extinction Books in Order

A weakened humanity faces invasion by advanced beings combining flesh and machinery. Targeted for capture, veteran Mitch Taylor must escape and rally Earth's defenders before the attackers overwhelm the planet and complete their campaign of annihilation.

As the battle for Richmond approaches, a scientist offers technology that could change the war. Taylor and Sommers set out to retrieve it, but a deadly trap threatens the marines and humanity's remaining chance to resist.

With Taylor critically injured and Sommers missing, Recon soldiers continue their resistance against Earth’s alien occupiers. Discovering an enormous facility for producing cyborg troops forces them into a race to destroy it before the enemy can overwhelm the remaining defenders.