"Behold the brown-faced men..."See in text(Text of the Poem)
A detail that lends credibility to the poem--cavalry troops, because they rode in the sun all day, were truly "brown-faced," a detail that only an observer would catch.
"A line in long array where they wind betwixt green islands..."See in text(Text of the Poem)
Whitman's source for this poem has been identified as a dispatch from a* New York Herald* correspondent who was watching cavalry from General Lovell Rousseau's command crossing the Coosa River at Ten Islands Ford in Alabama in July, 1864.
"hark to the musical clank..."See in text(Text of the Poem)
Cavalry troops during the Civil War often put a dent in their scabbards to keep the swords from rattling, but the rest of their equipment still made a lot of noise.