List of Medal of Honor recipients for World War I World War I ( also known as the First World War and the Great War ) was a global military conflict that embroiled most of the world ' s great powers , assembled in two opposing alliances : the Entente and the Central Powers . The immediate cause of the war was the June 28 , 1914 assassination of Archduke Franz Ferdinand , heir to the Austro - Hungarian throne , by Gavrilo Princip , a Bosnian Serb citizen of Austria – Hungary and member of the Black Hand . The retaliation by Austria – Hungary against Serbia activated a series of alliances that set off a chain reaction of war declarations . Within a month , much of Europe was in a state of open warfare , resulting in the mobilization of more than 65 million European soldiers , and more than 40 million casualties — including approximately 20 million deaths by the end of the war . When World War I broke out , the United States maintained a policy of isolationism , avoiding conflict while trying to negotiate peace between the warring nations . However , when a German U - boat sank the British liner " Lusitania " in 1915 , with 128 Americans aboard , U . S . President Woodrow Wilson demanded an end to attacks on passenger ships . Germany complied and Wilson unsuccessfully tried to mediate a settlement . He repeatedly warned that the U . S . would not tolerate unrestricted submarine warfare , in violation of international law . By the time the United States of America entered the war in 1917 — three years after the first shots were fired — several Americans had already gone to fight as pilots by joining the Royal Flying Corps . These pilots reported to Canada , and after flight training were sent to fight as officers in the British military . The Medal of Honor was created during the American Civil War and is the highest military decoration presented by the United States government to a member of its armed forces . The recipient must have distinguished themselves at the risk of their own life above and beyond the call of duty in action against an enemy of the United States . Due to the nature of this medal , it is commonly presented posthumously . As of 2015 121 men received the Medal for their actions in World War I ( 35 of them posthumously ) : 92 from the Army , 21 from the Navy , and 8 from the Marine Corps . Among the recipients were Alvin York , who later became the basis for the movie " Sergeant York " , and Edward Rickenbacker , who became a flying ace . Ralph Talbot of the Marine Corps also became a flying ace and was the first Marine aviator to receive the Medal of Honor . Since the Medal of Honor was established , 19 recipients have received it twice , of whom 5 received both awards during World War I . These 5 men were all Marines who received both the Army and Navy versions of the Medal of Honor for the same action . This was made possible by the practice of attaching some units of the U . S . Marine Corps , a part of the Department of the Navy , to larger U . S . Army commands , making Marines in such units eligible for both Army and Navy decorations . Of the other three Marines who earned the Medal of Honor during World War I , two were awarded only the Navy version and one , Fred W . Stockham , received only the Army version . In February 1919 , the criteria for the award were amended to state that no person could receive more than one Medal of Honor , thus precluding any future double recipients . In 2015 two previously overlooked soldiers were identified to receive the Medal of Honor for their actions in World War I . In a June 2 , 2015 ceremony at the White House in Washington , D . C . Private Henry Johnson and Sergeant William Shemin received the medal posthumously for their actions .