A-class destroyer (1929)

The A class was a flotilla of eight destroyers built for the Royal Navy as part of the 1927 naval programme. A ninth ship, HMS Codrington, was built to an enlarged design to act as the flotilla leader. Two similar ships, HMCS Saguenay and HMCS Skeena, were built for the Royal Canadian Navy.

Design
The A class were an Admiralty standard design based on the 1926 prototypes HMS Amazon and HMS Ambuscade. It was intended that the following alterations be made from the prototypes:
 * The guns were to be true Quick Firing (QF) pieces with full length shields, those in Amazon and Ambuscade were of the Breech Loading (BL) type, with two-part ammunition.
 * 'B' gun was to be carried on a High-Angle (HA) mounting giving 60° elevation
 * The torpedo tubes were to be quadruple instead of triple
 * Asdic (sonar), depth charges and high-speed destroyer minesweeps were to be carried
 * The separate cruising steam turbines were to be replaced by adding a cruising stage to the main turbine
 * A petrol generator was to be fitted, so that electric light and services could be provided when steam was down in harbour

In the event, the HA mounting was never fitted, along with the Asdic and most of the depth charges. The class were 200 tons heavier than the 1926 prototypes yet the only major improvement were the quadruple tubes. Speed was disappointing, being 35 kn with a deep load maximum of only 31 kn.

Acheron was given high temperature and pressure boilers (500 psi, 750 ° F) by Parsons Marine Steam Turbines to examine the weight and economy savings. Her specific fuel consumption was reduced from 0.8 lb −1 hp−1 hour−1 in her sisters to 0.6 lb −1 hp−1 hour−1. In the event the trials were inconclusive, and the Admiralty maintained an attachment to the 300 psi / 600 °F Admiralty boiler until the Battle class of 1942 which entered service in 1944, some ten years after other major Navies.

Codrington
HMS Codrington was built to an enlarged design - 343 ft (105 m) compared to 320 ft (98 m) - to accommodate Captain (D) (in Royal Navy parlance, the commander of the destroyer flotilla) and his staff; some 47 additional officers and men. She shipped a fifth 4.7 in gun between the funnels, and with 39000 shp made 37.7 kn on trials. However, the increased length made her somewhat unhandy, having a turning circle much greater than the standard A class, which resulted in complicated flotilla manoeuvres.

Canadian ships
The two Canadian ships were designed to be of a similar performance and specification to the British ships to allow them to tactically combine. They had their bows strengthened with heavier plating to enable them to perform in areas with ice, with a large metacentric height to allow for the build-up of ice and snow on the upperworks. Their length was three feet less than their British counterparts, and their displacement also decreased, although only slightly. The ships were built by John I. Thornycroft & Company in Woolston, Hampshire and had the broad, slab-sided funnels characteristic of that builder.

War modifications
It is unlikely that the early war losses Codrington, Acasta, Acheron and Ardent received any major alterations. In 1941 the surviving ships had the after funnel cut down in height and the after torpedo tubes replaced by a First World War era QF 3 inch 20 cwt anti-aircraft gun on a Mk. IV HA mounting, a somewhat token addition. More of an improvement was landing 'Y' gun and the minesweeps and fitting Asdic and racks and throwers for a 10-pattern depth charge salvo, 70 rounds being carried. Two Oerlikon 20 mm cannon were fitted, one in each bridge wing. Achates had 'A' gun replaced by a Hedgehog anti-submarine (A/S) mortar and had the Type 271 centimetric Radar for detecting surfaced U-boats. Others had a Type 286F or 290 metric Radar added, the former of which had a fixed antennae array and required the ship to be turned to change the bearing down which it scanned. By 1942, the Canadian ships generally had 'B' and 'Y' guns removed, a Type 286 Radar added, no torpedoes, a 12 pdr gun, six single 20 mm Oerlikon guns and stowage for 141 depth charges.

By 1943, Antelope had a Type 271 Radar, and Type 286 and 290 sets, where fitted, were replaced with the Type 291. The 12 pounder gun was removed around 1943 and High Frequency Direction Finding (HF/DF, or "huff-duff") was generally added. The single 20 mm guns in the bridge wings were replaced by Mark V powered mountings for twin weapons, the singles replacing the ancient 2 pounder guns amidships. In 1944 Active, Anthony and Antelope received a pair of 6 pounder / 10 cwt QF Mark I guns on a Mark I* mounting in lieu of 'B' gun. This automatic weapon was fitted for dealing with E-boats on east coast duties.

Service
The class saw much service in the Second World War, being involved in convoy protection and anti-submarine warfare in home waters and the North Atlantic. Seven of the eleven ships of the class were sunk in World War II. Acasta and Ardent were sunk on 8 June 1940 by the German battleships Scharnhorst and Gneisenau west of Narvik during the Norwegian campaign. Codrington was sunk by German air attack at Dover on 27 July 1940. Acheron was sunk by a mine off the Isle of Wight on 17 December 1940. Achates was sunk by two large German heavy cruisers, Admiral Hipper and Lützow. Arrow was so badly damaged when the ammunition ship SS Fort la Monte blew up on 4 August 1943 at Algiers that she could not be repaired and was towed to Taranto and paid off. Skeena was wrecked in a storm off Iceland on 25 October 1944. Saguenay was heavily damaged in a collision with the merchant ship Azara and was consigned to the role of a training ship after being repaired.

The surviving ships were worn out from war duties and were scrapped soon after the war.