He fought the government to stop slavery from spreading, and end it too. This poem was written and took place in the late fall. Many clues lead to me believing this. Also many lines in the poem refer to the autumn leaves falling from the trees and the fields being bare. The sheaves are also referred back to several times.
Sheaves are bundles of grain or tall grass bound tightly into large stacks.
I think the sheaves are kind of a symbol of life. Therefore I do believe that the Master-Reaper is a symbol of God once a person dies they will go into heaven, and lay down their lives at the Lord s feet, but this is just my faith. Somebody else might take it as something else. I think this poem is either written in the point of view of an African American or an abolitionist. I took sheaves as either one of his many speeches or his life, and to bring them to the government or to heaven.