More (#2) from The Making of the Atomic Bomb:

After Alexander Sachs paraphrased the Einstein-Szilard letter to Roosevelt, Roosevelt demanded action, and Edwin Watson set up a meeting with representatives from the Bureau of Standards, the Army, and the Navy...

Szilard began by emphasizing the possibility of a chain reaction in a uranium-graphite system. Whether such a system would work, he said, depended on the capture cross section of carbon and that was not yet sufficiently known. If the value was large, they would know that a large-scale experiment would fail. If the value was extremely small, a large-scale experiment would look highly promising. An intermediate value would necessitate a large-scale experiment to decide. He estimated the destructive potential of a uranium bomb to be as much as twenty thousand tons of high-explosive equivalent. Such a bomb, he had written in the memorandum Sachs carried to Roosevelt, would depend on fast neutrons and might be “too heavy to be transported by airplane,” which meant he was still thinking of exploding natural uranium, not of separating U235.

Upon asking for some money to conduct the relevant experiments, the Army representative launched into a tirade:

"He told us that it was naive to believe that we could make a significant contribution to defense by creating a new weapon. He said that if a new weapon is created, it usually takes two wars before one can know whether the weapon is any good or not. Then he explained rather laboriously that it is in the end not weapons which win the wars, but the morale of the troops. He went on in this vein for a long time until suddenly Wigner, the most polite of us, interrupted him. [Wigner] said in his high-pitched voice that it was very interesting for him to hear this. He always thought that weapons were very important and that this is what costs money, and this is why the Army needs such a large appropriation. But he was very interested to hear that he was wrong: it’s not weapons but the morale which wins the wars. And if this is correct, perhaps one should take a second look at the budget of the Army, and maybe the budget could be cut."

"All right, all right," Adamson snapped, "you'll get your money."