The emergency ships escorted, screened and conducted combat patrols. One example sets eighteen destroyers alongside five cruisers, a capital ship and a carrier. The destroyers make up most of the ships in that example and take on much of the routine work that lets the rest of the fleet operate. Knowing which destroyers were present helps explain what that force could do.
Notable Point · 1:12:44-1:14:07
What destroyer names reveal in an order of battle
An order of battle can name every cruiser and still leave most ships anonymous if it gives only a destroyer count.