13. Credits
• Department of Defense, A French assault on German positions, 1917, Public domain.
• Reichard und Lindner, Wilhelm II. on picture postcard, 1905 , Public Domain.
• Department of Defense, Grand Fleet Sails, January 1, 1923, Public Domain.
• Austria, Franz ferdinand and Family,1902, Public Domain.
• GNU
• Germany, A warning issued by the Imperial German Embassy, 1915, Public Domain.
• Department of Defense, The Lusitania's Last Voyage, 1907, Public Domain.
• heatheronhertravels, Trenches at Vimy Ridge, October 26, 2010 via Flickr, Creative Commons License.
• Library of Congress, President Woodrow Wilson asking Congress to declare war on Germany, April 2, 1917, Public Domain
• Rama, Musee-de-lArmee, July 11, 2006 via Flickr, Creative Commons License.