From the American battle Monuments website:

"Belleau Wood is located on the high ground to the rear of Aisne-Marne American Cemetery south of the village of Belleau (Aisne), France. In the center of the road leading through the woods is a flagpole and a monument commemorating the valor of the U.S. Marines who captured this area in 1918.
It commemorates the actions of the 4th Marine Brigade of the U.S. Army’s 2nd Division. The 2nd Division attacked German positions beginning on June 6, 1918. The 4th Marine Brigade liberated Bouresches that day. Its 5th and 6th Marine Regiments fought in Belleau Wood through most of June 1918.
Their gallant actions resulted in the Battle of Belleau Wood ending on June 26. On June 30, 1918, the Commanding General, French 6th Army, officially renamed Belleau Wood as “Wood of the Marine Brigade.”
The 2nd Division sustained casualties of 8,100 officers and men during the intense fighting in this vicinity during June 1918. Vestiges of trenches, shell holes, and relics of the war to include weapons found in the vicinity, may be seen near the Marine monument, which was erected by the U.S. Marine Corps."