1. World War I Photos

2. Archduke of Austria Franz Ferdinand, center right, and his wife Sophie, center left, walk to their car in Sarajevo on June 28, 1914. This photo was taken minutes before the assassination of the Archduke and his wife, an event which set off a chain reaction of events and would eventually lead to World War I. AP

3. Mobilization for war is proclaimed in Germany in August, 1914, at the start of World War I. Three Lions

4. English troops are handed flowers while marching through London on the way to war. Bettmann/Corbis

5. A soldier saying goodbye to a loved one in the rain at Victoria station, London, as he leaves for the front. Topical Press Agency/Hulton Archive/Getty

6. The British Grand Fleet under admiral John Jellicoe on their way to meet the Imperial German Navy’s fleet for the Battle of Jutland in the North Sea. AP Battle of Jutland = Date: 31 May – 1 June 1916; Location - North Sea, near Denmark Result: Tactically inconclusive; British dominance of the North Sea maintained

7. Allied troops landing on the beach at Gallipoli in 1915. Central Press/Hulton Archive/Getty

8. A woman standing on an electric shop truck at Watervliet Arsenal in Watervliet, New York, during World War I. Library of Congress

9. A soldier in a deep German trench in 1915. Hulton Archive/Getty

10. In this undated file photo, a Canadian soldier helps an injured German soldier. AP

11. Members of a British Highland regiment in a trench in 1915. Topical Press Agency/Hulton Archive/Getty

12. The German army cycle corps in a forest. Topical Press Agency/Hulton Archive/Getty

13. The first 5,000 American soldiers to reach England march across historic Westminster Bridge in London in 1917. AP

14. A sign in Washington D.C. during World War I, promoting food conservation. Library of Congress

15. An African American unit of infantry troops, marching northwest of Verdun, France, during World War I. Library of Congress

16. An Italian Alpine Regiment move up the Rurtor Glacier. Topical Press Agency/Hulton Archive/Getty

17. A soldier guards the inside of a rock bunker at an alpine defense position in Italy during World War I. Courtesy of the Museo Centrale del Rinascimento, Complesso del Vittoriano/AP

18. Bi-planes flying in formation. World War one was a pivotal time in the history of aviation, as the war was the first instance of aviation used on such a scale in combat. Hulton Archive/Getty

19. In this undated file photo, the cathedral in the town square of Ypres, Belgium, is in ruins after bombing in World War I. AP

20. A patrol of British soldiers marching into Cambrai, France during World War I. Bettman/Corbis

21. American troops, near St. Mihiel, France, cheer after hearing the news that the Armistice has been signed, ending World War 1, in 1918. AP

22. A parade of American World War veterans. Library of Congress