On June 16th, 1917, Germany sent the Zimmermman Telegram to Mexico. Germany's plan was to help Mexico invade the United States, to keep the Americans from intervening in Europe. Germany would then unleash total submarine warfare upon the British Navy, blockade Britain, and negotiate a peace with the UK and France. British agents intercepted the telegram, informed the other Allies, and then it was impossible for Mexico to invade under so much pressure?