Although Operation Sea Lion was never attempted, there has been much speculation about its hypothetical outcome. The great majority of military historians, including Peter Fleming, Derek Robinson and Stephen Bungay, have expressed the opinion that it had little chance of success and would have most likely resulted in a disaster for the Germans. Fleming states it is doubtful whether history offers any better example of a victor so nearly offering his vanquished foe an opportunity of inflicting on him a resounding defeat. Len Deighton and some other writers have called the German amphibious plans a "Dunkirk in reverse". Robinson argues the massive superiority of the Royal Navy over the "Kriegsmarine" would have made Sea Lion a disaster. Dr Andrew Gordon, in an article for the "Royal United Services Institute Journal" agrees with this and is clear in his conclusion the German Navy was never in a position to mount Sealion, regardless of any realistic outcome of the Battle of Britain. In his fictional alternate history "Invasion: the German invasion of England, July 1940", Kenneth Macksey proposes that the Germans might have succeeded if they had swiftly and decisively begun preparations even before the Dunkirk evacuations, and the Royal Navy for some reason had held back from large-scale intervention, though in practice the Germans were unprepared for such a speedy commencement of their assault. The German official naval war historian, Vice Admiral Kurt Assmann, wrote in 1958: "Had the German Air Force defeated the Royal Air Force as decisively as it had defeated the French Air Force a few months earlier, I am sure Hitler would have given the order for the invasion to be launched - and the invasion would in all probability been smashed".