My introduction to alternative history was Philip K.Dick’s The Man in the High Castle, which I read when I was about 20. I hesitate to call it my favourite, though.That prize goes to Len Deighton’s SS-GB, which combines an interesting alternative timeline where the Nazi invasion of Britain takes place with a detective/espionage thriller. Since Len Deighton has also written some pretty good popular historical books on related subjects (e.g., Fighter and Blitzkrieg), I took his ideas as being fairly accurate.
And now here comes Derek Robinson, whose books I also enjoy, who enjoys getting to the heart of matters – at least as he sees them – which he has done in novels such as A Piece of Cake and Damned Good Show, in which he explores the myths that have grown up around the historical episodes he is writing about. So Invasion 1940 is there to prove to the reader that the Battle of Britain, though important, had very little to do with stopping Operation Sealion (the planned Nazi invasion of Britain).

Robinson points to the dysfunctional nature of the German armed forces. Thanks to Hitler, who played a divide and conquer game with the different armed forces, there was never any coordination between the services. At the top, the generals, marshals and admirals were all engaged in empire building. Göring with his bejewelled marshal’s baton and massive wardrobe of comic-opera uniforms (who appears as a character in my Beneath Gray Skies) was just one example, albeit the most flamboyant. The lack of coordination meant that there was little realistic chance of any amphibious invasion succeeding.
He also points out that the Allied invasion of France took four years to plan, and had been preceded by several smaller invasions which enabled the development of tactics and matériel. The Germans had nothing other than river crossings, such as the Meuse, on which to base their plans, and in fact, the Channel was regarded initially as just a very large river. There were no dedicated landing craft, the German army relied on horses, rather than mechanised transport, and anyone who has looked at the logistics of moving and supplying an animal-based army will realise the difficulty of moving such an army across water – and keeping it moving on the other side.
Skipping over the air battles, which I’ll come to later, though Robinson puts them at the centre of his book, we come to the practicalities of the invasion. As mentioned, there were no landing craft, simply a mass of requisitioned and clumsily adapted river barges. These would have taken more than two days to reach their objectives in some cases, being capable of being towed (or in some cases moving under their own power) at 4 or 5 knots. To protect them, the Germans would have had fewer than ten destroyers available, against over 60 Royal Navy craft, which were capable of swamping and sinking the barges with their bow waves alone.
Paratroops, the boogeymen of the invasion forces? Robinson describes these as ludicrously overrated. The German parachutes were non-steerable, and were attached to the back of the Fallschirmjäger, necessitating a horizontal leap from the aircraft (the slow unarmed Ju52) – and worse. The paratroops’ weapons were supplied in a separate container, which had to be located, maybe a few kilometers away from the troops, and emptied before the troops were armed with anything more than a knife and a pistol.
Ultimately, the logistics and scale of an invasion that would have succeeded were impossible, in Robinson’s view. The Royal Navy would have made mincemeat out of the invasion fleet (assuming it could ever have been assembled at the right time with the right weather and tides).
But what about “the Few”?

I think any serious historian (indeed, any historian with a pretence at being serious) will agree that the Air Ministry’s and the Luftwaffe’s claims of losses and kills are wildly inaccurate (and were known to be inaccurate at the time). Robinson applauds the courage of the young men who went up, fighting a lonely and cold war which demanded courage, skill, and not a little insanity, it would appear (Robinson compares the RN “Salt Horse” destroyer captains to fighter pilots).
Along the way, there are many interesting facts brought into play. I knew about the carburettor Merlin versus the fuel-injected DB 601 (Robinson considers this equal to if not superior to the Merlins of that day) and its effect on tactics and handling, and rear seat armour, but not about the design of the 109’s seat which gave the German pilots certain advantages in high-G manoeuvres..
What the Battle of Britain did not do, Robinson says, was to stop the invasion. What it did do was to show Britain, and the rest of the world, that the “unstoppable” Nazi war machine, in the form of the Luftwaffe, was indeed vulnerable. There are technical reasons why the battle went the way it did – for example, the refusal of the Luftwaffe to fit drop tanks to the Bf109-Es, the overuse of Bf110s as Zerstörer heavy fighters, as well as elements of luck – head winds causing Luftwaffe formations to take longer than expected to arrive, and giving the RAF time to prepare for their arrival, cloud cover, and others, but it does not take away from the basic fact that the British were fighting for their country (along with foreign fliers who were fighting for revenge) against men who were fighting for some kind of abstract ideal.
So… you may not agree with his conclusions, but it’s worth a read, and worth checking up some of the sources.
PS Robinson’s novels, both the WW1 and WW2 novels, are great reads. A lot of black humour, and sudden death, but totally in keeping with the mindsets of the protagonists.