How many large opposed landings were there in the ETO/MTO between a small Dieppe and a large Normandy? I would suspect that a lot more was learned on Sicily and the boot of Itally than on that raid. It was the lessons that they learned at Dieppe that convinced them not to try to take a port in the first stages of an invasion of France. I can't see this. It only influenced the degree of how badly an army was beaten. It was THE decisive battle of the Normandy campaign and pretty much ended all major German resistance in France. I think that's pretty cruical. But how greatly did they influence the war? The British Army would have never ended up on Japanese soil by that route and Japan didn't have the ability by then to extend into Eastern India, much less hold it. It was a turning point for the men on the ground. Much like Stalingrad. What about Alam el Halfa? The Eighth Army loses here and El Alamein does not happen. Yes, quite. I'd agree with that.