I was watching a program on WWI and when they said that Gallipoli was the largest amphibious assult up to that time. That started me thinking, what lessons of what not to do were learned in that clusterfuck that Eisenhower specifically incorporated into the D-Day invasion?
I’m not especially well-versed in the Gallipoli campaign, but I would have thought the issues there were mostly the usual WWI issues - trying to attack dug-in machine guns with infantry, etc. The lessons of what not to do at Normandy would have been learned more at Dieppe.
The advent of air power, AFVs, and a host of specialized landing craft changed amphibious operations out of all recognition in thirty years. For lessons they would have looked to much more recent operations, principally TORCH, SHINGLE, AVALANCHE and JUBILEE [if only for how not to do it]
As well as Operations in the Pacific. (Guadalcanal, Tarawa.)
I’d have to say that the biggest lesson learned was the importance of getting beyond the beaches rapidly, in hours, not days. This lesson led to both tactical changes and changes in equipment. The airborne invasion, the Higgins boat, air superiority, tanks landing in the first wave, etc., all of these were aimed at speed. Some things worked better than others, but if you look at what was intended, clearly, they wanted to leave the beaches behind.
In other words, when you get ashore, you don’t quit for the day to rest and have tea (one major assault at Gallipoli failed for just this reason. By the time the British got moving again the Turks controlled the heights).
There was a lack of drive, particularly from Stopford and to an extent, Hamilton.