Who is the speaker? what is he/she like? what is the tone of this speaker's

The speaker of this poem is the dead man himself just talking in second person.

The person is remorsed. He might have done something that he is not proud of in the battle so he's reflecting on the matter and refers to himself as an animal. The there is a dark tone to this poem.

It could also be that what he's done is going to be a burden on him and follow him till he dies because at the end he says "en route to its grave". So he isn't dead or maybe he is being figurative as in his soul his going there which is why he refers to himself as an animal.