I've been reading
In Pale Battalions by Robert Goddard (An excellent book BTW) and searched for the poem that inspired the book's title and epigraph. The author, Charles Hamilton Sorley, was killed in World War I. This poem was found among his belongings after his death.
“When You See Millions of the Mouthless Dead”
When you see millions of the mouthless dead
Across your dreams in pale battalions go,
Say not soft things as other men have said,
That you’ll remember. For you need not so.
Give them not praise. For, deaf, how should they know
It is not curses heaped on each gashed head?
Nor tears. Their blind eyes see not your tears flow.
Nor honour. It is easy to be dead.
Say only this, “They are dead.” Then add thereto,
“yet many a better one has died before.”
Then, scanning all the overcrowded mass, should you
Perceive one face that you loved heretofore,
It is a spook. None wears the face you knew.
Great death has made all this for evermore.