April 6, 2017, marks the 100th anniversary of the U.S. Declaration of War resolution against Germany and subsequent entry in "The Great War" (World War I). The United States remained neutral as war raged in Europe from summer 1914 to spring 1917. However, matters changed when Germany broke its pledge to limit submarine warfare in January 1917.
In response to the breaking of the Sussex pledge, the United States severed diplomatic relations with Germany. On January 16, 1917, British cryptographers deciphered a telegram from German Foreign Minister Arthur Zimmermann to the German Minister to Mexico, von Eckhardt, offering Mexico U.S. territory in return for an alliance with Germany. Known as the Zimmerman telegram, it helped draw the United States into the war after it was widely published in U.S. newspapers. On April 2, 1917, President Woodrow Wilson gave a Joint Address to Congress requesting a declaration of war against Germany. The Senate approved the resolution by a vote of 82-6 on April 4, 1917. Two days later on April 6, 1917, the House adopted the declaration of war resolution against Germany by a vote of 373-50. On December 7, 1917, Congress approved a resolution declaring war with Austria-Hungary, Germany's allies. See CRS Report RL31133, Declarations of War and Authorizations for the Use of Military Force: Historical Background and Legal Implications.
The U.S Army pre-WWI strength consisted of a volunteer force of 200,000 men (127,588 Regular Army and 80,446 National Guard), insufficient to meet the demands of a land battle in Europe. This led Congress to pass the Selective Service Act on May 18, 1917, requiring all men between the ages of 21 and 30 to register for military service, but conscription proved low. Congress amended the Selective Service Act in August 1918, to expand the draft age. As a result, more than 2 million were inducted from the 24 million men registered.
During the early days of the war, a service flag with a Blue Star was used to represent each person, man or woman, in U.S. military service. When a servicemember was killed, an accepted practice developed to replace the Blue Star with a Gold Star. Gold Star Mothers and Gold Star Families are those who suffered the loss of their loved ones in military service; and this recognition continues today.
According to the Department of Veterans Affairs factsheet on America's Wars, from 1917 to 1918, a total of 4,734,991 U.S. servicemembers participated with 116,516 casualties (53,402 battle deaths and 63,114 non-battle deaths). An additional 204,002 were wounded. For a breakdown by service, see CRS Report RL32492, American War and Military Operations Casualties: Lists and Statistics.
In May 1917, General John Joseph "Black Jack" Pershing was designated the supreme commander of the American Army in France, known as the American Expeditionary Forces (AEF). In June 1917, the first group of the AEF deployed to France. Over the course of the war, the AEF participated in 13 major land battles starting with a French offensive in Cambrai alongside British forces in November 1917, and ending with the Battle of Vittorio Veneto, Italy, in November 1918. The Meuse-Argonne Offensive along the Western Front, from September 26 to November 11, 1918, was one of the most significant battles, with 1.2 million AEF participating over 47 days with 26,000 U.S. casualties. For detailed history, see the Army's Order of Battle of the U.S. Land Forces in the World War, 1917-1919.
The war officially ended when the Treaty of Versailles was signed on June 28, 1919. However, fighting ceased earlier on Armistice Day, November 11, 1918, effective on the 11th hour of the 11th day of the 11th month. In 1919, President Wilson proclaimed November 11 as the first commemoration of Armistice Day in the United States. It was later changed to Veterans Day (Public Law 380) on June 1, 1954, making November 11 the day to honor American veterans of all wars. The last surviving American WWI veteran, Frank Buckles, died in 2011 at age 110.
In 1923, Congress enacted legislation establishing the American Battle Monuments Commission (ABMC) for the construction of WWI monuments and cemeteries. According to the ABMC list of WWI Burials and Memorializations, "of the 116,516 Americans that lost their lives, 30,974 are interred at overseas American military cemeteries and 4,455 are commemorated on the Tablets of the Missing as missing in action, lost, or buried at sea."
H.R. 6364/P.L. 112-272 (01/14/2013). The U.S. World War I Centennial Commission Act was created "to establish a commission to ensure a suitable observance of the centennial of World War I, to provide for the designation of memorials to the service of members of the United States armed forces in World War I, and for other purposes." See the Centennial Commission website for details.
H.R. 2366/P.L. 113-212 (12/16/2014). The World War I American Veterans Centennial Commemorative Coin Act directs the Treasury Secretary to mint and issue $1 silver commemorative coins subject to a $10 surcharge per coin to assist the World War I Centennial Commission in the commemoration.
H.R. 3979/P.L. 113-291 (12/19/2014). The Carl Levin and Howard P. ''Buck'' McKeon National Defense Authorization Act for FY2015. "Section 3091, Commemoration of the Centennial of World War I. (a) The Liberty Memorial of Kansas City, Missouri is designated the World War I Museum and Memorial; and (b)(1) the redesignation of Pershing Park in Washington, DC, as the National World War I Memorial."
H.R. 5937/P.L. 114-227 (09/29/2016). This act authorizes the ABMC to enter into an agreement with the Lafayette Escadrille Memorial Foundation to acquire, operate, and maintain the Lafayette Escadrille Memorial in Marnes-la-Coquette, France. The ABMC shall ensure the ongoing maintenance of the memorial and cemetery containing the remains of the first U.S. aviators who died during WWI. The 38 volunteer American aviators, known as the Lafayette Escadrille, fought under French command before the United States entered the war. April 20, 2016, marked their 100th anniversary.