Farewell to Barn and Stack and Tree

when two contrasting things are placed near one another in order to emphasize that contrast

it can be seen in the second stanza when the seemingly pastoral landscape is contrasted with the dead man. 

It occurs when words are used in succession, or at least appear close together, and begin with the same letter. 

“Farewell to barn and stack and tree,

Farewell to Severn shore.

Terence, look your last at me,

For I come home no more."

“The sun burns on the half-mown hill,

By now the blood is dried;

And Maurice amongst the hay lies still

And my knife is in his side."

The first two lines of this stanza are shocking. They contrast the warmth, heat, and color of the sun, to that of the “half-mown hill” and the dried blood.  

“My mother thinks us long away;

‘Tis time the field were mown.

She had two sons at rising day,

To-night she’ll be alone."

“I wish you strength to bring you pride,

   And a love to keep you clean,

And I wish you luck, come Lammastide,

   At racing on the green."

“Long for me the rick will wait,

And long will wait the fold,

And long will stand the empty plate,

And dinner will be cold.”