Beat! beat! drums! Blow! bugles! blow! Make no parley—stop for no expostulation;
Again, our speaker urges the drums and bugles to play. Third time's a charm?
They shouldn't even stop for conversation or make any explanations. (Now this is some major personification: how would instruments make explanations? Well, maybe now he's thinking of the people playing those instruments.)
So, even if our speaker wants everyone to drop what they're doing and pay attention, it's not for an explanation.
It seems like the war isn't the sort of thing that can be explained. It's a force that just sweeps through. And besides, wars don't tend to stop so that they can be explained to anyone who questions their significance.
Mind not the timid—mind not the weeper or prayer;
Our speaker now tells the instruments to pay no attention to people who are uncertain, crying, or praying. That sounds pretty harsh.
But, you know what? War probably doesn't care about the fear and sadness it creates – at least that's the point our speaker seems to be making.
Again, our speaker's emotions and intentions are kind of hard to read. It could be that he honestly thinks these sad and frightened people should be ignored. He might be gung-ho about this being the time to sacrifice and get into the war effort.
But the fact that he notices and mentions these people makes us suspect that he has at least some sympathy for them.
Also, notice that we get more repetition here ("mind not"). All of these repetitions create a sense of marching rhythm in the poem, and also make us understand that these imperatives aren't flexible. They can't be negotiated.
Mind not the old man beseeching the young man;
Our speaker tells the instruments not to pay attention to an old man pleading with a young man. So, what's going on in this scene?
Perhaps an old man is begging a soldier to leave. Or perhaps it's an old father begging his son not join the army.
Whatever it is, it's probably heartbreaking.
Again, it seems that the music and the band and the war are all pretty ruthless.
Let not the child's voice be heard, nor the mother's entreaties. Recruit! recruit!
Our speaker also wants the music to cover up the voices of children and mothers, and he urges the military band to recruit men for the war.
Okay, now things are a little clearer. Men are being recruited to fight in the war.
The fathers and sons are enlisted, never mind how their children, wives, and mothers feel about it.
Geez. This is really hard to read. We picture the mother and children screaming out and being totally and completely ignored. It seems harsh, but by mentioning the child and the mother, our speaker calls our attention to them. It gives some emotion to the otherwise rhythmic and feelingless war that we've seen so far in this poem. So in a weird way, even while he's saying their voices shouldn't be heard, he is highlighting their suffering.
But then it's cut off – just like that – with those harsh words: "Recruit! recruit!".
Make the very trestles shake under the dead, where they lie in their shrouds awaiting the hearses, So strong you thump, O terrible drums—so loud you bugles blow.
Now our speaker wants the drums and bugles to play so powerfully that the very foundation shakes under some dead folk. (A trestle is a supporting beam.)
Who are these "dead?" It doesn't seem clear. They could just be whoever has died in the town recently, by old age or accident.
But mentioning them here, right after we find out for sure that men are being recruited for war – well, it makes us think of those who are dying, or will die, in the war. It's almost like a foreshadowing of the fate of many of the people being recruited.
And again we wonder: is our speaker really as excited about this war and this recruiting as he acts? If he is, why does he spend so much time bringing to our attention the suffering and pleading? Why does he turn our attention to "the dead" at the end of the poem? Why does he call the drums "terrible?"
Well, war is a complex force with complex effects on people and the world. It makes sense that our speaker's emotional response to it would also be complex.
And one last thing: notice how in the last line, our speaker is no longer giving an imperative. Now he seems to just be observing. Once the war is in full swing, there's just no ignoring it. And definitely no controlling it.