The Device That Won WW2: A History of the Cavity Magnetron
hackaday.com
hackaday.com
After all, the Soviets fought on the eastern front, without the magnetron. Quoting https://archive.org/details/ofarmsmen0000robe/page/286/mode/... :
> If weapons won the the war for the Soviet Union, it was tanks, most particularly the T-34, which epitomized this superiority. Designed in August 1939 by the Medium Tank Design Group, the T-34 was the culmination of nearly a decade of extensive research on a wide range of components. The product was a masterpiece of integration, incorporating for the first time a powerful and fireresistant diesel engine, a high-velocity 76-mm gun (German Panzer III and IV tanks mounted 37mm and 50-mm pieces), thick armor sloped to deflect shells, and advanced Christie suspension, combined with very wide tracks to provide exceptional mobility in snow and ice—all in a compact package weighing barely thirty tons.
I personally don't know how to judge which is accurate, or estimate what the result would have been without, say, the magnetron.
Each item on its own contributed to the war effort, absolutely. The cavity magnetron and the RADAR it enabled saved lives in the Battle of Britain, the PTO and elsewhere thanks to its early warning of incoming air raids, to be sure. To claim any single item was decisive is pretty tough, though, when compared against broader concepts like disparity in industrial base, logistical ability, and so on.
To the T-34 example you quote, how well would the T-34 have performed without locomotives to bring fuel, consumables, and the tanks themselves to the front? Or the resources to the tank factories in the first place?
Another amazing topic in this regard is the battle of the beams over Britain.