Submarines add reach but invite anti-submarine warfare

The submarine is an important extension of the torpedo rather than a final answer. World War I illustrates its early potential because many surface ships lacked effective means of countering it; HMS Dreadnought's ramming of a submarine makes the point vividly. Later sonar, depth charges, anti-submarine mortars, and homing torpedoes show how a new naval weapon can generate the systems that constrain it. Even a homing torpedo becomes a reciprocal threat once surface forces can aim the same principle back at submarines. A torpedo's nominal maximum range also differs from a practical firing distance because a target already moving or turning away may outrun the weapon's fuel.