The opening years of war are fought with the prewar fleet

Wartime production cannot quickly replace a force lost or found inadequate at the outbreak of conflict. Britain could bring a relatively simple Flower-class corvette into service quickly, but destroyers and larger warships required much longer. Major British wartime construction did not enter service in noticeable numbers until around 1942, leaving the first three years to the ships already available. The D class illustrates the consequence because its delayed refits left old but indispensable cruisers carrying current operations. The same lag would constrain a future Pacific conflict: industrial scale cannot eliminate the time needed to turn capacity into trained, operational warships.