I would suggest Walt Whitman as being one. I took a course with the University of Iowa titled: Whitman's Civil War: Imaging Loss, Death and Disaster which looked at Whitman's poetry. It focused on how his poetry evoked the realities of the war, the sense of carnage and loss. He was very closely associated with the sick and dying, offering what support he could to them in the hospitals, and was deeply moved by their suffering, as well as the suffering produced in general by war.
'Drum-Taps is a collection of poetry by American poet
Walt Whitman. The book, which was written during the
American Civil War, was first published in 1865.
An essential companion to reading
Drum-Taps is Whitman's autobiographical memoir,
Specimen Days. This part of Whitman's work recounts his everyday experiences and the effect they had on his psyche. Relating mostly with the middle section of
Drum-Taps, it reveals how the dominant metaphor for the war is a hospital, filled with wounded men who need treatment and dying men who need to be comforted.'
(Taken from 'Drum Taps' - Wikipedia)