April 2—President Wilson asks congress to declare that acts of Germany constitute a state of war; submarine sinks American steamer Aztec without warning. April 4—United States senate passes resolution declaring a state of war exists with Germany. April 6—House passes war resolution and President Wilson signs joint resolution of congress. April 8—Austria declares severance of diplomatic relations with United States.
April 9—British defeat Germans at Vimy Ridge and take 6,000 prisoners; United States seizes fourteen Austrian interned ships. April 20—Turkey severs diplomatic relations with the U.S. April 28—Congress passes selective service act for raising of army of 500,000; Guatemala severs diplomatic relations with Germany.
May 7—War department orders raising of nine volunteer regiments of engineers to go to France. May 14—Espionage act becomes law by passing senate. May 18—President Wilson signs selective service act. Also directs expeditionary force of regulars under Gen. Pershing to go to France. May 19—Congress passes war appropriation bill of
$3,000,000,000.
June 5—Nearly 10,000,000 men in U. S. register for military service. June 12—King Constantino of Greece abdicates. June 13—Gen. Pershing and staff arrive in Paris. June 15—First Liberty loan closes with large over-subscription. June 26—First contingent American troops under Gen. Sibert arrives in France. June 29—Greece severs diplomatic relations with Teutonic allies.
July 9—President Wilson drafts state militia into federal service. Also places food and fuel under federal control. July 13—War department order drafts 678,000 men into military service. July 14—Aircraft appropriation bill of $640,000,000 passes house; Chancellor von Bethmann-Hollweg's resignation forced by German political crisis.
July 18—United States government orders censorship of telegrams and cablegrams crossing frontiers. July 19—New German Chancellor Michaelis declares Germany will not war for conquest; radicals and Catholic party ask peace without forced acquisitions of territory. July 22—Siam declares war on Germany. July 23—Premier Kerensky given unlimited powers in Russia. July 28—United States war industries board created to supervise expenditures.
August 25—Italian Second army breaks through Austrian line on Isonzo front. Aug. 28—President Wilson rejects Pope Benedict's peace plea.
September 10—Gen. Korniloff demands control of Russian government. Sept. 11—Russian deputies vote to support Kerensky. Korniloff's generals ordered arrested. Sept. 16—Russia proclaims new republic by order of Premier Kerensky. Sept. 20—Gen. Haig advances mile through German lines at Ypres. Sept. 21—Gen. Tasker H. Bliss named chief of staff, U.S. army.
October 16—Germans occupy islands of Runo and Adro in the Gulf of Riga. Oct. 25—French under Gen. Petain advance and take 12,000 prisoners on Aisne front. Oct. 27—Formal announcement made that American troops in France had fired their first shots in the war. Oct. 29—Italian Isonzo front collapses and Austro-German army reaches outposts of Udine.