The Cressys were designed against the torpedo threat visible to naval architects in the late 1890s. Their numerous twelve-pounders were intended to destroy attacking torpedo boats before those craft reached an effective firing position. Submarines existed only in tiny numbers and had not yet demonstrated the operational threat seen in 1914. The ships did have torpedo defenses, but those defenses addressed a surface delivery platform. A sound response to an identified threat could still fail when the means of attack changed.
Notable Point · 57:32-58:58
The torpedo threat the Cressys were built to defeat
The class did carry defenses against torpedo attack, but its quick-firing guns were intended to stop surface torpedo boats rather than submerged submarines.