At the beginning of 1917 Germany decided to resume all-out submarine warfare on all commercial ships headed toward Britain, realizing that this decision would almost certainly mean war with the United States. Germany also offered a military alliance to Mexico, as intercepted and decoded by the British in the Zimmerman Telegram, and publication of that offer outraged Americans just as German U-boats (submarines) started sinking American ships in the North Atlantic. Wilson asked Congress for "a war to end all wars" that would "make the world safe for democracy", and Congress voted to declare war on April 6, 1917.