What does the poem the zonnebeke road by Edmund blunden mean?

the first stanza tells of soldiers relieved from their watch and are frozen by the cold. last line in 1st stanza is humorous as isnt the whole war gloomy for no reason?

2nd stanza refers to England by showing their life in the trenches is worse and that life and nature has merged in no man's land and the last line means that the war is unworthy of respect or consideration.