The anniversary was Friday, which I missed. Thankfully, it was noted by Belmont Club:
Something else happened on a June 6. General Pershing, Commander of the AEF said of it, ‘the Battle of Belleau Wood was for the U.S. the biggest battle since Appomattox and the most considerable engagement American troops had ever had with a foreign enemy’”. On that day on June 6, 1918:
the casualties were the highest in Marine Corps history to that point. Overall, the woods were attacked by the Marines a total of six times before they could successfully expel the Germans. … One of the most famous quotations in Marine Corps lore came during the initial step-off for the battle when Gunnery Sergeant Dan Daly prompted his men forward with the words: “Come on, you sons of bitches, do you want to live forever?”