Trade protection works as a layered operation

Commerce warfare explains why a cruiser need not defeat every threat alone. Smaller cruisers can ambush or damage a surface raider, forcing it into harbour or slowing it until a battlecruiser, carrier, or other force arrives. Their value is therefore part of a wider system of pressure, pursuit, and reinforcement. The River Plate example makes mission-killing the raider, rather than winning an isolated gun duel, the relevant measure of success.