The steel helmet was introduced to the German army in 1916. The units shown are ordinary units. Everybody wears "feldgrau" - field grey why the coloring sould have more grey tone instead of olive. Behind the Kaiser and GEN v. Hutier Leibtrompeter des Kaisers (trumpeter of the Kaiser) in his anachronistical peace time uniform.
When I first saw this I really wondered if even one of those soldiers would be older than 18. They all looked so young on the first glance. I canīt help but be amazed how you colour these pictures. All the details in your pictures are impressive.