Shock, dread, like a void/empty, pensive and melancholy.
Why?
There is morbid detail in this poem which relates to soldiers of war who have died.
Despite their honorable sacrifice in war, in modern times, they have become forgotten (highlighted by the indifference of the conductor) and have become associated with the grass of the Earth.
This relates to a much quoted verse from the Old Testament of the Bible “All men are flesh”.
The main principle is that men are born of dust and shall once return as dust/soil (to the Earth) - elements of this are also true even for non-believers - carbon cycle.
Historical connection sometimes implies the positive and negative effect of a certain subject from its past up to its future effects. So for example, the connection of the peoples point of view before and after a bombing incidents. I hope this will help you. Have a nice day
