Paul Fussell explains:

The process by which, as the war went on, these Georgian metaphoric sunrises and sunsets turned literal and ghastly can be observed in "Before Action," a poem written by William Noel Hodgson two days before he was killed in the Somme attack. Writing as if during the last sunset before the next day's attack, he begins his three-part prayer with a Ruskinian survey of benefits received:

By all the glories of the day
And the cool evening's benison,
By the last sunset touch that lay
Upon the hills when day was done,
By beauty lavishly outpoured
And blessings carelessly received,
By all the days that I have lived
Make me a soldier, Lord.

We are still in the purlieus of the Georgian understanding of "Beauty." But as he writes Hodgson knows that the forthcoming attack will take place in the early morning, and the final stanza, while maintaining its focus on traditionally significant times of day, signals an awareness of the actual situation a day hence. The "familiar hill" is both metaphoric and literal, or rather it is a metaphor caught in the act of turning literal: the hill is at once the lucky eminence of youth and the actual observation post where the speaker has watched with too little feeling "a hundred" sunsets preceding morning attacks like the one in which he will now take part:

I, that on my familiar hill
Saw with uncomprehending eyes
A hundred of Thy sunsets spill
Their fresh and sanguine sacrifice,
Ere the sun swings his noonday sword
Must say goodbye to all of this:
By all delights that I shall miss
Help me to die, O Lord.

Spill, fresh, sanguine: with those terms the two dimensions of the poem merge into one. Georgian figure and discovered actuality merge; the red of sunset is seen as identical with the red of freshly shed blood. With sacrifice, the poem, although still maintaining its pose of abstract literariness, turns to face actual facts, and we realize that it is no longer talking about sky effects and Literature but about people and action. Without rudeness or abruptness, Ruskin has been invited to squat in a jump-off trench on a hill near Albert.

(The Great War and Modern Memory, 61)