- US formally declared war on April 6th of 1917
- First troops came with Gen. Pershing on May 26th ("Lafayette, we are here")
- American Expeditionary Forces (AEF) started deployment in France by the Autumn of 1917
- AEF divisions entered serious action in mid 1918 with the second Battle of the Marne river which is considered as the turning point of the war on the western front and the famous Battle of Bois Belleau (Belleau Wood, where the US Marines illustrated)
- The African-American, the Buffalo Soldiers of the 92d and 93th infantry division entered the fight earlier. As a consequence of the racial policies of these times they weren't allowed to participate with the AEF and they were put under French command until the armistice.
To aggregate these dates into a single one the French government choose to celebrate the "American Entry" into Bastille Day's parade on July 14th as a tribute to American decisive help in the Great War 100 years ago.
President Trump and the First Lady attended the parade in which American troops (Army, Navy, Air Force and Marines) showed (in today's and period uniform) as well as F-22 Raptor aircraft.
Pictures of the parade will soon be seen on the Internet.