Galactic Convoy by Bill Baldwin

THE EMPIRE'S BRAVEST SPACE WARRIOR

Helmsman Wilf Brim ahs been assigned to the maiden voyage of the Defiant - first in a new class of warships built to protect Imperial convoys from the ravaging League of Dark Stars. From deepest space tot eh seas of a primitive world, t the desolate ruins of ancient star forts, Wilf's job is to battle savage raider hordes...even as he dares to fight of the forbidden love of beautiful Princess Margot Efer'wyck.

Then Brim discovers that the raiders possess a sinister "bender" device that renders ships invisible; and that a vast, undetectable Leaguer armada is bearing toward the imperial worlds of the Haelic Run. Wilf and his comrades must now find and unlock the lost, secret knowledge to defeat the League's mysterious weapons and superior numbers - or vital supplies, the war, and Princess Margot will be doomed...