We intend to begin unrestricted warfare on the first of February. We shall endeavour in spite of this to keep the United States neutral. In the event of this not succeeding, we make Mexico a proposal of alliance on the following basis: mak…

In the three weeks that remained, Zimmermann devised an insurance policy. If unrestricted U-boat warfare increased the likelihood of America entering the war, then Zimmermann had a plan that would delay and weaken American involvement in E…

A swift victory was essential. Unrestricted submarine warfare and the inevitable sinking of US civillian ships would almost certainly provoke America into declairing war on Germany. Bearing this in mind, Germany needed to force an Allided …