Standing up to the abuse a heavily armed warship can dish out is difficult. The best protection is distance and speed; it's very hard for anything to hit a ship hustling at 0.3 or 0.4c unless the pursuer is able to match course and speed. Once a battle ensues, the combatants have only a few choices to bolster their ship's defenses: chaff, jammers, point-defense guns, deflection fields, and various types of hull armor. Chaff consists of tiny strips of metallic foil launched by a simple rocket; the rocket explodes and the chaff blooms into a huge cloud, covering the ship. Jammers interfere with radar or communication signals. Fire control and missile seekers can be scrambled by a jammer, as well as some sensors. Point-defense guns use rapid-fire guns to create a wall of projectiles between a missile and its target. Deflection fields are created by hull-mounted gravitational arrays. By emitting intense gravity fields, these fields can deflect energy weapons around a ship and stop physical projectiles outright. This defense is expensive and consumes a lot of power.

Finally, hull armor varies from nonexistent to formidable. The lightest forms include polymeric and cerametal armor. Polymeric armor is made from engineered plastics, much like carbonate fiber. Cerametal armor consists of sandwiched plates of laminated ceramics and lightweight metals. Alloy armor consists of large quantities of supertough metals, such as vanadium steel. Neutronite armor is the densest, strongest material known, but it's also extremely expensive. Only wealthy nations can afford to outfit their entire navy in the stuff; most make do with lighter armor for the smaller, faster ships, keeping their limited supply of neutronite for the finest ships of the fleet.