When Zimmerman was sworn in, America rejoiced at what they thought was going to be a new era of German diplomacy, and the greater likelihood of peace in Europe. But little did they realize that the new foreign minister was intent on increasing Germany’s aggression. Two years into the war, Zimmerman successfully lobbied for a lift on the ban on unrestricted submarine warfare. He believed that a new fleet of U-boats could lead to Britain’s surrender within six months; the only issue was America’s neutrality. This new move would almost certainly push America’s allegiance to the Allies, so Zimmerman devised a cunning plan: he would persuade Mexico to declare war on America, which would allow time for Germany to win in Europe and prepare for the American campaign. But thanks to a clever move by British ships, Germany’s underwater cables had been severed before the war, so Zimmerman’s encrypted telegram to Mexico was intercepted by the UK.
Admiral Hall’s cryptanalysis deciphered parts of the telegram, and correctly deduced what Zimmerman’s plan was. But Hall decided to not to tell America for two reasons: he did not want to miss vital information and give America an incomplete message, and he did not want the Germans to figure out that Britain had broken their encrypted messages. Admiral Hall was justified in his decision to not give the message immediately to America.
The decision to allow unrestricted U-boat warfare would have gone through in either scenario, and such a drastic move on Germany’s part might have been enough to push America to fight for the Allies. But the more important reason that Hall’s decision was justified was that Hall was sacrificing the short-term consequences for the long term gains. If the Germans knew that Britain could crack their codes, that would have been enough of an impetus for the Germans to develop a stronger encryption; thus, the British would have lost a major source of intelligence that would have proven disastrous, possibly fatal later in the war. The long-term effects of being able to know the plans of your enemy, their locations, and modes of attack are invaluable; either way, when America chose to remain neutral after the resuming of unrestricted boat warfare, Hall exploited the Zimmerman telegram to pull America into the war.
Although Hall’s decision may seem unethical on the surface, the long-term benefits significantly outweigh the short-term negatives.
