The seller claims this is a u.s. Army ww1 helmet. If it is, should it have all those battles marked on the side? I know that Americans weren't in Verdun, yet it's possible that the person was there in the aftermath. The markings are scratched in the helmet, which isn't unusual. Also, I'm not an expert on ww1 helmets, so please tell me if its u.s. or british. Also, the unit is marked on the front, so any help with that would be appreciated! Thanks

This is a US m1917 helmet, and it is not uncommon to see Incised decoration on WWI helmets.

 

While the US did not participate in the 1916 battle of Verdun for obvious reasons, American troops fought over the same ground in 1918. Judging by the 66, and the list of locations, I'd guess that this belonged to a doughboy in the 66th Field Artillery Brigade, which was detached from the 41st Division and served (less the 147th FA) as 1st Corps Artillery.

Cool! Thanks for all that info. It is much appreciated