Analysis of A Death Song

What cometh here from west to east awending?
And who are these, the marchers stern and slow?
We bear the message that the rich are sending
Aback to those who bade them wake and know.
Not one, not one, nor thousands must they slay,
But one and all if they would dusk the day.

We asked them for a life of toilsome earning,
They bade us bide their leisure for our bread;
We craved to speak to tell our woeful learning;
We come back speechless, bearing back our dead.
Not one, not one, nor thousands must they slay,
But one and all if they would dusk the day.

They will not learn; they have no ears to hearken.
They turn their faces from the eyes of fate;
Their gay-lit halls shut out the skies that darken.
But, lo! this dead man knocking at the gate.
Not one, not one, nor thousands must they slay,
But one and all if they would dusk the day.

Here lies the sign that we shall break our prison;
Amidst the storm he won a prisoner's rest;
But in the cloudy dawn the sun arisen
Brings us our day of work to win the best.
Not one, not one, nor thousands must they slay,
But one and all if they would dusk the day.