Cobra trilogy

EARTH'S ONLY HOPE WAS THE COBRAS

The colony worlds Adirondack and Silvern fell to the Troft forces almost without a struggle. Outnumbered and on the defensive, Earth made a desperate decision. It would attack the aliens not from space, but on the ground—with forces the Trofts did not even suspect.

Thus were created the Cobras, a guerilla force whose weapons were surgically implanted, invisible to the unsuspecting eye, yet undeniably deadly.