Free Engineers of Victory: The Problem Solvers Who Turned the Tide in the Second World War by Paul Kennedy Page B

early 1943 continued unabated, so the convoys that did sail in late March suffered enormous physical damage; yet the two main ones, HX 230 and SC 123, got through with only one vessel sunk to the U-boats. The same was true of the early April convoys, HX 233 and ONS 3 and 4. The only convoy that met with serious attack at this time was HX 231, whose escorts fought off a whole group of U-boats on April 5 and 6, inflicted much damage, and brought the vast bulk of its cargoes to port. No fewer than twenty-two of the sixty-one vessels were oil tankers, while many of the others were carrying what might be termed “pre-D-Day” supplies—trucks, tanks, aircraft, landing craft, and vast amounts of ammunition. 21 This, of course, was key. Just getting that one huge group of oil tankers alone to Britain staved off the island’s resource crisis of early 1943.
    And there was to be even better news ahead. The powerful winds and great long rollers of the North Atlantic never abated, but the sound of conflict now did. Amazingly, only fifteen merchantmen were lost in those waters between June and mid-September 1943, and only one of them was in a convoy. As the Allies girded themselves for further advances in the Mediterranean and for a really massive buildup of men and munitions in Britain in preparation for the future invasion of France, and as the demands of the Pacific and Southeast Asia campaigns grew ever greater, their shipping crisis actually intensified. But that crisis was essentially one of supply and demand, eventually solved by further stupendous outputs of American industry, and no longer about the hemorrhaging of ships from the convoy routes between New York/Halifax and the Clyde/Merseyside. To the tens of thousands of crew members of the merchant vessels who for the first time steamed those rough seas without a single attack, this must have seemed incredible, inexplicable, even a bit eerie. More U-boats were being sunk than merchantmen.
    One graph captures this dramatic change of fortunes in the Battle of the Atlantic during the months of 1943.
    U- BOAT VS . M ERCHANT S HIP L OSSES IN THE N ORTH A TLANTIC , 1943
The dramatic rise in U-boat losses and decline in Allied merchant ship losses during the critical months of 1943 are well captured here.
    Before we understand the swiftest of the changes of fortune in the five major campaigns of the Second World War, it is appropriate to study the critical convoy battles of May 1943, especially the first, since it was the most important of all. It focused, unusually, around the voyage of one slow,
westward
-bound convoy, ONS 5, which sailed from its gathering place near the Clyde for North American ports between April 23 and May 11. Here was the reprise to the saga of SC 122 and HX 229. This time the Allies won—not easily, but quite decisively. The map on this page captures the overall situation.
    Forty-three merchant ships, emerging from five separate British ports, had gathered off the Mull of Kintyre with their escorts in late April and then set off on a great-circle route to the New World. They were not holding much cargo, but the point was that if they did not get back to America’s eastern ports, there would be fewer and fewer Allied vessels left to carry oil, ores, trucks, grain, and aircraft parts to the British Isles in the future. And it was emphatically an
Allied
convoy: in addition to the twenty-eight vessels flying the Red Duster, there were five ships from the United States, three from Norway, two from theNetherlands, two from Greece, and one each from Yugoslavia, Panama, and Denmark. Escort Group B7 consisted of two destroyers and a frigate, two rescue trawlers, and four invaluable corvettes named, deliciously,
Sunflower, Snowflake, Pink,
and
Loosestrife.
In charge of the escort was Commander Peter Gretton, whose consuming passion was the sinking of U-boats; he had recently returned from the Mediterranean, where he had received the Distinguished Service Order (DSO)