Making like the Civil War, 50 years after the fact
At first glance, with the kepis, droopy mustaches, buttoned-backed greatcoats, sword bayonets, and square tarred knapsacks with blanket bedrolls strapped tightly on top, I thought these troops were blue-coated Union volunteers mugging for Matthew Brady around the 1860s.
Turns out they are soldiers of the French Republic’s 124th Infantry Regiment de Laval posing in Pierrefonds, Oise Department, Northern France, in early 1915 with 8x50mmR Lebel Fusil Modèle 1886/M93 rifles. Notably, by mid-1915 the French Army uniform got a lot more modern to included the Adrian helmet and “horizon-blue” uniforms of a simpler cut.
On that note, here is Sgt. Joseph Dore, 7th New York State Militia. Carrying full Government-Issued kit in 1862, via the Library of Congress, for comparison.