One of the photo-illustrated history books I made a beeline for in my elementary school library described the German army marching through the streets of Brussels in 1914 as (to the best of my recollection) “an endless sea of ghostly grey uniforms” with “the hobnails of their boots making sparks at night.as they struck the cobblestones.”
This was taken from an eyewitness account, presumably written by a foreign correspondent from a neutral country (maybe the USA?). It’s too early for William L Shirer; any idea who it might be?