For the fuel problem, PLUTO was ingenious and it set in motion many innovations that allowed the Middle East oil fields to be exploited but arguably, was a failure in terms of fuel logistic support to Allied forces in Western Europe
Tankers offloading at ports delivered vastly more, although only when risks of enemy action had reduced.
TOMBOLA on the other hand, exceeded all expectations, it was a great success.
Perhaps lest discussed aspects of Mulberry was the counter productive inter-service and international rivalry, hubris, resistance to change and a general ‘not invented here’ attitude that beset the project from start to finish.
The Admiralty insisted it knew about port construction (it didn’t), the War Office (Army) insisted it knew about maritime towing (it didn’t) and the US Navy insisted the whole scheme was a waste of time (it wasn’t.
This conspired to rob Mulberry of much of its potential.
It was only the inspirational leadership and dogged persistence of a collection on civilians, British Army, Royal Navy, US Army, US Coastguard and US Navy officers that overcame these difficulties to produce the end result.
At a technical and operational level collaboration and joint working were excellent but this was not always apparent at higher levels and the problems were compounded by labyrinthine command and control structures used by both forces. For a number of reasons, not least a general antipathy to the concept from the US Navy, the US construction teams did not have enough time for training and thus, did not follow the correct mooring procedures for the Whale/Beetles and placing of block ships.
They were advised by British personnel but the warnings were not heeded, and Mulberry A suffered because of it.
It has become somewhat fashionable to compare the post storm offload using DUKW, Rhino ferries and LST at Omaha to Mulberry B and declare Mulberry a failure, but that misses several critical elements.
The Mulberry harbour was a system, the Phoenix caissons and block ships provided the calm water that enabled the Rhino, DUKW and LST equipment to be used. Without these, only a tiny fraction of the offload rate could have been achieved, certainly not enough to sustain the invasion force which would have been severely hampered.
Phoenix and block ships were essential to both methods of offload.
This leaves the other components, namely Bombardon and the Pier head/Whale offloading platform and roadway.
The Bombardons were the greatest failure, although in their defence, they were operated in conditions far exceeding their known parameters. In hindsight, they were a complete waste of steel, manpower and building facilities that could have been used for other purposes such as shipping or in lieu of the concrete Beetles that proved so troublesome.
After the storm, they were not reinstated.
Which leaves the pier head and roadway open to question.
None of the Allies knew beforehand about the favourable soil conditions at Omaha that allowed heavy construction plant to cut beaching channels for the LST’s that allowed turnaround times to be reduced, a tactic that was simply impossible to predict possible until after the storm, so there may well be an element of being wise after the fact in praising the LST beaching method.
Tonnage offload rates are also rather a simplistic measure that do not consider low volume stores or the importance of one particular cargo or the other. Mulberry B would eventually be used for the vast majority of vehicular and bridging offload, for example.
However, a valid criticism of the pier head was that offload rates were not improved by employing experienced stevedores or employing modern electric cranes, despite being suggested by none other than Churchill himself.
The whole Mulberry system was designed around the British LST Mark 2 and 3.
The LST buffer pontoon was almost an afterthought but proved vital. They allowed the LST to approach, discharge, return to England and be half way back to Normandy in the same time it would take one to beach, discharge and then wait for the tide to re-float it. Although the US beaching of LST’s at Omaha would enable over the beach throughput rates to be maintained at comparable rates to the pier heads, it created problems elsewhere. The LST’s being used at Omaha were unable to be redeployed to other locations further up the coast and in the Pacific theatre as per the original plan.
Using LST’s longer than anticipated at Omaha, therefore, simply shifted problems elsewhere.
Cherbourg validated the Allies assumptions that port denial is both very easy to do and very hard to correct, there is no doubt an alternative was needed i.e. Mulberry
In general, Mulberry was a success that proved its worth, staying open longer and enabling greater offload rates than originally planned.
Mulberry is often seen as a wholly British affair but this is incorrect, US expertise played a key role at various stages, a joint success in the truest sense of the word, despite the numerous problems described above.
Perhaps the final word is best left to someone from the other team;