Deterrence and patrols are difficult naval work to make visible

Patrols, training, and a fleet held ready at Scapa Flow could look like inactivity to readers following battles on land. Those duties sustained naval presence and deterrence, whose success often meant that an attack did not occur. Continued classification of Cold War patrol records makes their purpose harder to explain even after the submarines concerned have left service. The 1917 destroyer-allocation example shows the related problem of explaining force requirements: more than 300 Royal Navy destroyers still left a shortage south of Ireland once other commitments were met.