1. Ten vessels are sunk with the loss of 8 lives on the first day of unrestricted submarine warfare.
3. The United States severs diplomatic relations with Germany. Count von Bernstorff is given his passports.
6. Fourteen ships, including the passenger steamer "Port Adelaide," are sunk by submarines in the war zone.
8. Brazil, Peru, Chile, Uruguay, Bolivia, Panama, Cuba, and Argentina refuse to recognize the German blockade.
10. Ambassador Gerard leaves Germany.
16. British troops in Mesopotamia force the Turks back on the Tigris.
22. Seven Dutch steamers torpedoed by a German submarine while sailing supposedly under a safe conduct from Germany.
24. Kut-el-Amara captured by British.
25. The British attacking German positions on the Ancre capture Serre.
26. President Wilson asks authority to arm merchant ships.
28. The U.S. government publishes a communication from Zimmermann, German foreign minister, to the German minister at Mexico City, suggesting an alliance against the United States whereby Mexico would be given opportunity to reconquer Texas, New Mexico, and Arizona.