A Norwegian special-forces ski-team infiltrated a Norwegian power-plant that was making heavy-water, which is what the Germans were using for their research, and sabotaged all the vats and sunk a ship carrying supplies … killing a number of innocent countrymen in the process.
https://en.wikipedia.org/wiki/Norwegian_heavy_water_sabotage
This slowed down the already hamstrung German research effort.
Meanwhile in the US they built a new city, school-system and all, dedicated to supporting the staff to create the bomb.
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