On December 20, Morgenthau marched over to State, taking Pehle and Paul along for ballast. They had spent the morning rehearsing a script for the showdown. Morgenthau’s aim was not only to deliver a stern warning, but to get all the cables. Only the originals, all agreed, could convince FDR of the State Department’s deception. Morgenthau’s aides had coaxed him into a scheme to play Hull: to ask for a copy of cable 354, casually, without revealing its importance. In Hull’s office, Paul felt the weight of the occasion. Morgenthau, he would say, “was taking his political life in his...