alt Hacker NewsClickbait antidote: The cubes revealed only that the uranium was a bit less dense than textbook values because of tiny internal voids.
That measurement fed a computer model, but if I'm reading the article right, most of the work was actually based on wartime records on heavy water and graphite. Anyway, the model showed they would have needed twice the uranium and heavy water they actually had.
IIRC, US Colonel Hogan got Luftwaffe Colonel Klink to drink a bunch of that heavy water as a cure for baldness as a truckful of it transited through Stalag 13.
Phew, that underground mission was more important than I thought!