The Sands of Saturn (Imperium, #3)

Britannians on the March
With the Carthaginians pushed inside the walls of Londiumun, the Britannians can finally stop reacting and take the fight to them. Hoping to retake the British Isles and even add new allies to the Alliance, legions are dispatched to Ériu, the emerald isle, to push back Carthaginian expansion there.

Ky, a test pilot from the future and now Consul for the Britannic Empire, knows that Carthaginian retaliation is coming and prepares an explosive new surprise for the invaders.