Page 12 – United States of America


United States flag

1917 Map

Map of USA

Click on map for more detail

General facts

  • Population: 103 million (1917)
  • Capital: Washington DC (1917 population 350,000)


  • Head of State and Head of Government:
    • President Woodrow Wilson (4 March 1913 – 4 March 1921)
    • President Warren Harding (4 March 1921 – 2 August 1923)

Participation in the War

  • Entered the war: 6 April 1917 (USA declared war on Germany)
  • Ceased hostilities: 11 November 1918 (armistice with Germany)
  • Ended belligerent status: 2 July 1921 (unilateral declaration by US government formally ending the state of war between USA and the former Central Powers, Imperial Germany and the Austro-Hungarian Empire)  

The United States delegation to the Paris Peace Conference signed the Treaty of Versailles in June 1919. To President Wilson’s frustration, the final vote on its ratification by the US Senate on 19 March 1920 was effectively won by its opponents, who prevented its supporters getting the two-thirds majority required (the vote was 49 yeas to 35 nays).

The Senate opposition to the Versailles Treaty had arisen mainly in reaction to the collective security provisions in the Covenant of the League of Nations, which was to be established under the treaty. They saw these as an unconstitutional constraint on America’s freedom of action in international affairs. Some ‘isolationists’ believed membership of the League would force America to get involved in conflicts it would otherwise stay out of.

Its failure to ratify the Versailles Treaty meant that the United States needed to make its own separate peace treaties with the former Central Powers and their successor states. The United States government took the first step in this process by unilaterally declaring the cessation of the state of war between itself and Austria, Germany and Hungary on 2 July 1921. This paved the way for the signing and ratification of separate peace treaties with these states on 24, 25 and 29 August 1921 respectively.

The United States never became a member of the League of Nations.

Military Forces

US Army

  • Peacetime strength 1917: 128,000
  • Reserves 1917: 131,500 (National Guard)

The American Expeditionary Force (AEF)

  • Total mobilised during the war: 4.7 million
  • Total sent overseas: 2.1 million

Upon the US entry into the war the government began raising a massively expanded army to serve in France for the duration of the conflict – the American Expeditionary Force (AEF). This was made up initially of soldiers from the peacetime Federal Regular Army and state-based National Guard units, but neither force could provide the colossal numbers of men called for under the AEF mobilisation plan. Some 72% of the personnel of the AEF were obtained by selective conscription – the draft. The Selective Service Bill passed into law on 18 May 1917 and 10 million American men registered with their local draft board in the first round of national registrations the following month (24 million would register by the end of the war).

The first units of the AEF arrived in France on 26 May 1917 to establish headquarters, reception depots and base camps for the troops who would follow. The first US troops did not go into the line on the Western Front until October, and even then only in very small numbers. This was partly because of the constraints of the AEF build-up, and partly the result of a US refusal to allow its troops to be placed within French or British divisions and under their command while the build-up took place.

General John Pershing, the commander of the AEF, insisted that he be allowed to build up an all-American field army that would fight only under American generals. Apart from the crisis caused by the German offensives of March–April 1918, he largely got his way. The result was that the bulk of the AEF did not engage in any serious fighting until the last six months of the war. In that short space of time American soldiers still paid a heavy price in blood, partly because of inexperience and sometimes unwillingness to fully incorporate the hard-won combat lessons of their French and British allies. In battles such as Belleau Wood, St Mihiel and the Meuse-Argonne offensive, casualties in attacking American infantry units were sometimes as bad as any in the opening clashes of 1914.


  • Peacetime strength 1917: 80,000
  • US Marine Corps: 15,000

Although the United States Marine Corps (USMC) was under the administrative control of the US Navy Department, the desperate need for experienced troops in early 1917 saw the 5th US Marine Regiment sent to France as part of the AEF – over the objections of the AEF’s commander, General Pershing, who wanted the AEF to remain an all-US Army force. The 5th Marine Regiment won great fame amongst the American public for its prominent role in the Battle of Belleau Wood in June 1918. This led to an expansion of the Marines’ strength in the AEF to a full brigade and a surge in voluntary recruitment at home. By war’s end the USMC had expanded to a strength of 72,000 men, of whom 24,000 were serving with the AEF in France.

Fleet (1917)

  • Battleships (Dreadnoughts): 14
  • Battleships (pre-Dreadnoughts): 23
  • Cruisers: 21
  • Light cruisers: 10
  • Destroyers: 50
  • Submarines: 39



  • Dead (all causes): 115,660
  • Wounded: 205,690
  • Total casaulties: 321,350


  • Thomas Hoff, US Doughboy 1916–19, Osprey, Oxford, 2005
  • Spencer C. Tucker (ed.), The Encyclopedia of World War I: Volume 4, ABC-CLIO, Santa Barbara CA, 2005
  • John Votaw, The American Expeditionary Forces in World War I, Osprey, Oxford, 2005
How to cite this page

'United States of America', URL:, (Ministry for Culture and Heritage), updated 5-Jun-2015