Onomatopoeia

Onomatopoeia (adjective onomatopoeic) is the use of words to imitate the sounds they are describing.

The quotation just given, followed by “the monstrous anger of the guns”, is an example of more than alliteration: it is also an example of Owen was trying to say what a battlefield of the first World War sounded like; in my view, he is remarkably successful in distinguishing between the deep, dull boom of heavy artillery (“monstrous anger of the guns”) and the crisper, sharper crackling of the ordinary soldiers’ rifles.