Any one lesson learned in tank design during WW2?

The_Chieftain:   I'm not sure that's accurate. Often times, in WW2, the side with the lighter armor tended to win. See France 1940, or France 1944. And then if you look at the vehicles which were produced after the war, the Germans and French came out with Leopard 1 and AMX-30, both of which sacrificed armor to a large extent for speed.   There is a place for heavy armor and a powerful gun, but I don't know if one can say it was a given that they should be present at the cost of speed and mobility. The opinion of the world's tank designers seemed to be split in the cold war period until engine and armor technology caught up to the point that one didn't necessarily have to make that choice any more. (This notwithstanding the Soviet matter of attempting to build tanks supportable in an offense involving built bridges and an increasing logistical trail)