Galactic Patrol (1937) by EE Smith (from Astounding Stories)

Galactic Patrol introduces Kimball Kinnison, who will be the hero of the next four books - Galactic Patrol, Gray Lensman, Second Stage Lensmen and (to a lesser extent) Children of the Lens. Kinnison and Clarissa MacDougall are the penultimates of the human breeding program the Arisians set up many eons earlier. The book deals with the earliest stages of Kinnison's career, starting with his graduation as a Lensman from the Patrol's academy. Organized pirates, known as Boskonians, have gained a great advantage with a new type of space drive, making their ships far faster than anything the Patrol can build. That is, with the exception of one ship, the Britannia. New and experimental, built to be the fastest thing in space, she has abandoned the traditional ray armament of a space ship for an offensive weapon much older - explosive artillery, fired at an opponent held in place by unbreakable tractor beams. Her mission is to capture a Boskonian ship of the new type intact enough to get the secret of her speed (hence the artillery, which the scientists of the patrol think can damage another ship enough to disable it without destroying the information they require). The experimental nature of her weapon means that she would be useless to a man experienced only in using the standard weapons of the time, so she is given to the inexperienced Kinnison to command...