Burning Sky Trilogy

Lieutenant Capp is integrating Royal Navy tech onto a battered ship from the Old Earth fleet when she gets orders to cross the so-called Roach Frontier and investigate a potentially hostile alien race. The insectoids have survived a genocidal war and are expanding aggressively toward human territory. She arrives to find a navy warship already lurking in the system, with Captain McGowan of HMS Peerless preparing a preemptive strike against an insectoid mining colony. 

With the short, brutal struggle between humans and insectoids ending in an apparent truce, the navy orders forces withdrawn beyond the Roach Frontier, hoping to avoid a destructive war against their new rivals. But when an ambitious human settlement and a colony of semi-feral insectoids clash in the Segovia System, the conflict quickly spirals out of control, with humans launching an invasion of mechanized troops, and insectoids responding with a rapid military buildup that threatens to push the war into an uncontrollable spiral of complete genocide.

With the allied colony on Hot Segovia abandoned and a massive insectoid armada threatening an invasion of the human and Hroom worlds, Drake, Tolvern, and Vargus fight a war across multiple fronts to stem the enemy tide. Meanwhile, Lieutenant Capp, the only person to have successfully communicated with the aliens, believes the insectoids intentions are not as destructive as they appear. Even as allied forces are pushed to the brink, she hatches a scheme to hand herself to the enemy in a desperate bid to restore peace.