There's a long, elaborate background story to the Zimmerman Telegram. It was written by a junior diplomat, signed off on by the foreign minister (who was preocc

There's a long, elaborate background story to the Zimmerman Telegram. It was written by a junior diplomat, signed off on by the foreign minister (who was preoccupied with growing military influence on the Kaiser to reintroduce unrestricted submarine warfare), blown up by British military intelligence led by a dude named "Blinker" Hall, and then didn't really do much about the entry into the war (Barbara Tuchman not withstanding). See The Zimmermann Telegram: Intelligence, Diplomacy, and America’s Entry into World War I by Thomas Boghardt for the whole story.