6 JUN--This Day in US Military History

1918 – The first large-scale battle fought by American soldiers in World War I begins in Belleau Wood, northwest of the Paris-to-Metz road.

In late May 1918, the third German offensive of the year penetrated the Western Front to within 45 miles of Paris. U.S. forces under General John J. Pershing helped halt the German advance, and on June 6 Pershing ordered a counteroffensive to drive the Germans out of Belleau Wood.
U.S. Marines under General James Harbord led the attack against the four German divisions positioned in the woods and by the end of the first day suffered more than 1,000 casualties. For the next three weeks, the Marines, backed by U.S. Army artillery, launched many attacks into the forested area, but German General Erich Ludendorff was determined to deny the Americans a victory. Ludendorff continually brought up reinforcements from the rear, and the Germans attacked the U.S. forces with machine guns, artillery, and gas.
Finally, on June 26, the Americans prevailed but at the cost of nearly 10,000 dead, wounded, or missing in action. This is first battle where the AEF experienced the heavy casualties associated with the Great War. It represents the embodiment of U.S. Marine Corps determination and dedication and served as a signal to both allies and adversaries that America was on the Western Front to fight.


https://thisdayinusmilhist.wordpress.com/2005/06/06/june-6/