A scene Whitman used several times was the look of the battlefield, complete with casualties, under the moon. It was one of his first introductions to the realities of war, as he crossed several such scenes until he found his slightly-wounded brother. Finding him mortally wounded, or dead, was one of Whitman’s recurring nightmares.
Look down fair moon
Look down fair moon and bathe this scene,
Pour softly down night’s nimbus floods on faces ghastly, swollen, purple,
On the dead on their backs with arms toss’d wide,
Pour down your unstinted nimbus sacred moon.
 Whitman, Walt. Drum-Taps: The Complete Civil War Poems. Kennebunkport, Maine; Cider Mill Press, 2015. 161