Speed and firepower before the First World War

River, early Tribal, and Beagle destroyers offered different compromises as the Royal Navy's battle line reached 21 knots. Reliable Rivers made roughly 25 to 26½ knots, the larger Tribals could reach 33, and the Beagle example made about 27. Heavier 4-inch guns became useful because destroyers increasingly had to fight one another as well as torpedo boats. The Beagle example combined a 4-inch gun, three 12-pounders, and larger 21-inch torpedo tubes. A cruiser screen making roughly 28 knots needed a faster destroyer escort, but the main battle line did not necessarily need the same expensive speed margin. Higher speed raised questions about machinery, hull stress, size, and the firepower the hull could carry.