What does Kemmerich's death symbolize in the book? support with references

Kemmerich literally symbolized death. Death is personified as draining Kemmerick's life away. As Kemmerick dies we can see death creep over his body, almost like a posession, "Death is working itself from within. It already has command in the eyes....." Death becomes a thing unto itself sucking the life out of Kemmerick's body.

It may symbolise death, marcus' maths mark did induce a darker mood throughout the starting chapters