Occasionally, one reads that British destroyers of the pre-war period were significantly smaller than their US counterparts. This is something of a myth, as a year by year and class by class comparison shows that the destroyers built by these two nations prior to 1943 were quite comparable in size.
By the terms of the London Naval Limitation Treaty of 1930, the size of destroyers was determined by their "standard displacement," which was calculated by a set of treaty-defined measurements. The US and British fleets were each limited to a total destroyer tonnage of 150,000 tons (152,400 metric tons) and individual ships were restricted to having a standard displacement of 1,500 tons (1,524 metric tons), with an allowance that 16% of the total tonnage permitted, or 24,000 tons (24,385 metric tons), could be used for destroyers weighing up to 1,850 tons (1,880 metric tons). These latter destroyers were generally known as "Leaders" or "Large Destroyers," although these terms were not used nor defined by the London Treaty. Gunnery armament was also restricted, with the largest caliber permitted being 13 cm (5.1").
Prior to June of 1934, the US had not commissioned a new destroyer since 1922. In contrast, the British had built two prototypes (Amazon and Ambuscade) in 1926 followed by the A through D destroyer classes. These destroyers ranged in size from the 1,173 ton Ambuscade up to the 1,540 ton Coddrington.
In 1934, the British built the E/F classes which were of 1,350 tons plus two Flotilla Leaders (FL) at 1,475 tons. This compares to the first US destroyers built in over a decade, the Farraguts, which ranged from 1,345 up to 1,395 tons.
In 1935-36, the British built the G/H classes which ranged from 1,335 up to 1,345 tons plus one FL of 1,485 tons and a second FL of 1,505 tons. The US built the Mahan class, which ranged from 1,450 tons up to 1,500 tons.
The London Naval Treaty of 1936 altered the displacement restrictions by combining small cruisers and destroyers into a single "light surface warships" category defined by the following phrase: "Vessels which do not carry a gun with a calibre exceeding 6.1 in. (155 mm.) and the standard displacement of which does not exceed 3,000 tons (3,048 metric tons)." This phrase formally eliminated the 1,500 and 1,850 ton destroyer categories denoted in the London Treaty of 1930. However, as the total tonnage of 150,000 tons (152,400 metric tons) remained in place, the desire by Britain and the US to build large numbers of destroyers effectively kept individual destroyer size around 1,500 to 1,600 tons (1,524 - 1,626 metric tons).
In 1937-38, the British built the I class which were of 1,370 tons plus a 1,530 ton leader. The US built the Gridley/Benham class, all of which were of 1,500 tons.
In 1938-39, we see the British building the 1,690 ton J/K classes plus two FL of 1,695 tons while the US built the Sims class of 1,570 tons.
Turning our attention now to the other area of pre-war destroyer construction, the "Large Destroyers" or "Leaders" specified under the London Naval Limitation Treaty, we have the US building in 1935-36 the Porter class which consisted of four ships of 1,850 tons and four of 1,805 tons. No British equivalents were built until the sixteen Tribals of 1937 which were all of 1,870 tons. Also in 1937, the US built the five Somers class which were all of 1,850 tons. Note that these thirteen US "Large Destroyers" brought the US right up to the 24,000 tons (24,385 metric tons) limit specified by the treaty for large destroyers while the sixteen British Tribals of 1937 exceeded that limit. The US built no more "Large Destroyers" after the Somers, but more Tribals were built in 1940-42 for the RAN and RCN. These additional Tribals were of 1,927 tons.
Let's take a break here, as this is approximately the start of the European War and the inglorious end of all Naval Limitation Treaty restrictions. As can easily be seen from the above comparisons, the contemporary destroyers built by each nation in a particular year were roughly of the same displacement, with the variation in displacement between them being about 10% or less. A similar comparison of the "Large Destroyer" classes shows even less variation in tonnage.
When comparing numbers rather than tonnage for this same period, the British have commissioned or launched, by my count, two prototype destroyers, 96 destroyers and FLs of the A-K classes and 16 "Large Destroyers" (Tribals), while the US has commissioned or launched 60 destroyers and 13 "Large Destroyers" (Porter/Somers). Even if there was a 10% individual weight advantage to the US in every class vs. class comparison - which I believe by now that I have made abundantly clear that there was most certainly not - the British enjoyed a clear 3 to 2 advantage in total numbers.
Continuing on now to the early war years, for Britain we see in 1940-41 the L/M classes of 1,920 tons plus two FLs of 1,935 tons and the N class of 1,690 tons plus one FL of 1,695 tons. On the US side, we see the Benson class at 1,620 tons.
We are now at the start of the 1941-1944 British War Emergency Classes. The hulls and machinery of these ships were essentially continuations of the previous J/K/N classes. Looking at 1941-42, we find the O/P classes of 1,540 tons plus two FLs of 1,550 tons and the Q/R classes of 1,705 tons plus one FL at 1,725 tons and a another at 1,750 tons. In the same 1941-42 period, US continues with the Benson class of 1,620 tons, followed by the Livermore and Bristol sub-classes of 1,630 tons.
At this point, the building of the pre-war, treaty-restricted designs is essentially finished. From this time onwards, each nation was building whatever size ship was needed for winning the war, unhindered by the artificial limits imposed by the pre-war treaties. So, the significantly larger British "1942 Battle" and "1943 Battle" classes and the US Fletcher/A.M. Sumner and Gearing classes fall into a different category and for that reason will not be considered in this essay.
A summary point that should be made here is that there was no real barrier to either nation building equal-size ships in any year prior to the end of the treaty restrictions. Both nations chose to build slightly smaller or larger ships in certain years in order to achieve larger numbers, more desirable offensive/defensive features, better seakeeping, constructional advantages or a combination of these and many other factors. The only limitation was that, whatever they chose to build, it needed to be in accordance with the 1,500/1,850 ton treaty limits. Other than operational needs, nothing prevented the British from building the I class at 1,500 rather than 1,370 tons or prevented the US from building the Farraguts at 1,500 rather than 1,350 tons. Or, for that matter, nothing prevented either nation from reverting to the 1,000 ton size of World War I destroyers. That freedom to build to whatever characteristics each nation determined was necessary was, after all, rather the point of all those Naval Limitation Treaties of the 1920s and 1930s - that each class of ship have an upper limit in individual unit size, a total weight of fleet tonnage, a restriction on gun caliber size, but that individual units could vary within those limits in whatever fashion was desired in order to meet the needs as determined by those countries. To the very limited degree that some British destroyers of the 1930s and early 1940s were smaller or larger than their US contemporaries or vice versa was strictly a matter of choice by the respective heads of those nation's navies and governments.
- 28 June 2005