There are more details about this compromise in here (pages 333-336): https://books.google.es/books?id=Tu5mAA ... &q&f=falseAs the result of conferences at Norfolk House (SHEAF headquarters) during the week of 13 February, a compromise shipping plan was worked out. SHAEF first proposed to reduce the current planning allocation by one LSI(H), 48 LST's, and 51 LCI(L)'s with a resulting loss of lift for 21,560 men and 2,520 vehicles. This loss would then be made up by overloading transports (APA's), carrying vehicles in the APA's, using AKA's (cargo ships) in the initial lift, and finding (presumably from new production) an additional 27 LCT's. This plan was subsequently revised to exchange the 6 AKA's with the Mediterranean theater for 20 LST's and 21 LCI (L)'s, on the grounds that the large cargo vessels could more easily be used in the calmer southern waters. The exchange would still leave an estimated two-division lift for ANVIL although it was doubtful whether Gen. Sir Henry Maitland Wilson (Commander-in- Chief Mediterranean) would accept the loss of tactical flexibility which use of the AKA's involved.41 The SHAEF compromise still left a shortage of about fifteen LST's. General Eisenhower requested allocation of at least seven more LST's from U.S. production. The remainder of the deficit would have to be made up by increased loading of LST's on the third tide (morning of D plus 1) and increased serviceability.
The serviceability rate of landing craft-or, in other words, the percentage of craft on hand which at any given date would be operationally available-was always a planning figure to conjure with. So narrow were the planning margins that a difference of 5 percent in the estimates of serviceability might mean the difference between adequate and inadequate lift for the assault. The serviceability rate was contingent chiefly on repair facilities and the stock of spare parts-both of which were critically limited in the United Kingdom.42 COSSAC in Outline OVERLORD had planned on an average serviceability rate of 85 percent for all craft and 90 percent for ships.43 These figures were substantially approved at the Quebec Conference. On advice of U.S. naval planners, however, the rate for U.S. craft was raised in January to 9 percent for LST's and 90 percent for LCT's. The British insisted on retention of the lower COSSAC figures. SHAEF accepted both estimates and distinguished in planning between U.S. and British craft, allowing the serviceability rate set by each country.44
The SHAEF shipping compromise was severely criticized by planners of 21 Army Group, mainly on the grounds that SHAEF considered the problem of providing lift only from a logistical and not from a tactical point of view. For example, they pointed out that SHAEF had not shown separately the Commando-Ranger lift for special assault missions against fortified positions. This separation was important, the army group planners argued, because there could be no question of loading to full capacity the LSI's carrying Commandos, and of course the excess capacity could not be used for lift of other assault troops. The SHAEF proposals, by pushing the loading of shipping toward the full theoretical capacity of the vessels, sacrificed flexibility, particularly in that they prevented the preloading in craft of adequate reserves. Army group thought it extremely important that reserve units for the assault waves be tactically loaded in craft so that their employment would not be affected by losses or time delays of the LCA (ship-to-shore) craft used in the initial assault. By increasing the personnel lift on the first tide of the assault without any corresponding vehicle increase, the SHAEF proposal either would land men who could not proceed with their task until their vehicles arrived, thus causing congestion on the beaches, or would compel half-loaded personnel ships to wait offshore, thus exposing both ships and men to unjustifiable risks.45
The validity of these objections was fully conceded by General Eisenhower, but he considered the sacrifices and risks worth accepting in order to permit the simultaneous diversionary attack on southern France. Although at first strongly opposed, General Montgomery at last agreed and the proposals were submitted to the British Chiefs of Staff.46 The Chiefs of Staff disapproved the compromise on the grounds, first, that it skimped both ANVIL and OVERLORD and, second, that the slow progress of the Italian campaign made the possibility of providing the necessary build-up forces for ANVIL "So remote as to be negligible."47 Employment, as planned, of ten divisions in southern France, General Brooke pointed out, would leave only twenty divisions to fight the critical battle of Italy and to meet "other commitments which might arise in the Mediterranean."48
According to these sources, it was ultimately the situation in Italy what doomed an ANVIL simultaneous with OVERLORD. But what if the Wallies had reached their goals in Italy by February and OVERLORD and ANVIL had been launched simultaneously and with the allocation of landing craft of the February compromise? How would this allocation have affected both operations?
Juan G. C.