I understand the general use of machine guns, rifles, and poison gas, but I haven't been able to find any specific weapons that were used other than the Springfield 1903 Rifle, the hotchkiss machine gun, and the Chautchat machine gun^1. Does anyone have any ideas of weapons that the German soldiers would have been using during the defense of belleau wood? Or any other weapons that used during the battle. Any help would be greatly appreciated.
^1 (https://www.mca-marines.org/mcaf-blog/2011/08/15/devil-s-paintbrush-maxim-machine-gun-belleau-wood)
Standard rifle of the German Army in WWI was the Maurer Gewehr 98, though the Karabiner 98A, B and AZ versions were popular with the regular infantry, but especially the elite Stosstruppen, as they were lighter and shorter, ideal for trench fighting. The 98AZ evolved into the Karabiner 98 Kurz, which was the standard rifle of the German Army in WWII.
Automatic weapons would have been the MG 08 and MG 08/15, the former being the standard German heavy machine gun, the latter being it's more numerous 'Light machine gun' version that had been in service in large numbers since April, 1917. I'd refer to the MG 08/15 more as a GPMG, since it was still very heavy, and required a lot of maintenance.
In terms of artillery, most of the American artillery would have been French pieces, either American manned or with French crews. The AEF essentially made use of an eclectic mix of French and British weapons and equipment until the armistice, though American weapons like the BAR and Browning M1917 .30 cal. were entering service towards the end.