When Lilacs Last in the Dooryard Bloom'd

Whitman uses a lot of imagery in "When Lilacs Last in the Dooryard Bloom'd." I found this prevalent throughout the whole poem, from the "loud in the pines and cedars dim, clear in the freshness moist and the swamp-perfume" to "And the white skeletons of young men, I saw them." From what I can tell, Whitman wrote this poem to describe the memories and aftermath of a bloody war. The poem also begins and ends with the description of a gray-brown bird. I think this most likely represents the peacefulness currently, which is why he sticks in the dark war memories in between the two instances of the bird. I see some sort of a rhyme scheme from lines 172 to 184, with repeated words at the ends of lines and words like "though" and "not" which sound similar. Besides imagery, there are examples of metaphors as well. For example, the "death's outlet song."