Dead Wake: The Last Crossing of the Lusitania

by Erik Larson

The telegram was from Germany’s foreign secretary, Arthur Zimmermann, written in a new code that was unfamiliar to Room 40. The process of rendering its text in coherent English was slow and difficult, but gradually the essential elements of the message came into view, like a photograph in a darkroom bath. It instructed Germany’s ambassador in Mexico to offer Mexican president Venustiano Carranza an alliance, to take effect if the new submarine campaign drew America into the war. “Make war together,” Zimmermann proposed. “Make peace together.” In return, Germany would take measures to help Mexico seize previously held lands—“lost territory”—in Texas, New Mexico, and Arizona. Hall had no doubt as to the telegram’s importance. “This may be a very big thing,” he told de Grey, “possibly the biggest thing of the war. For the present not a soul outside this room is to be told anything at all.” And that included even Hall’s superiors in the Admiralty.