“The Battle for the Mississippi” is the story of the campaign to defeat and pass the forts at St. Philip and Jackson, seventy-five miles above New Orleans on opposite sides of the Mississippi. Admiral Farragut was chosen to force a passage through the snarl of chains and hulks that barred the way, an assignment that he carried out successfully, laying New Orleans open to the Union forces.
Melville’s first two stanzas are general and introductory, but the next four are put together from scraps of items scattered through the various reports given in the Rebellion Record, Volume IV, Doc. 510-525. The third stanza is a description of the confusion that reigned the night of the battle:

Some of this description probably derived from Admiral Farragut’s account:

The smoke was so dense that it was only now and then you could see anything but the flash of the cannon and the fire-ships or rafts, one of which was pushed down upon us . . . and in my effort to avoid it ran the ship on shore, and then the fire-raft was pushed alongside . . . (Doc. 522).

The Varuna, under Commander Boggs, made the trip through the fire-rafts successfully, but soon found itself “amid a nest of rebel steamers” (Doc. 515). It fought valiantly, setting afire and blowing up five rebel vessels before being butted by two iron-clads and run ashore in flames. These events are narrated in Commander Boggs’s official report (Doc. 515), from which Melville’s lines in stanza four were probably derived:

The remaining lines of the same stanza describe another event taking place at about the same time:

The sinking of the celebrated ram Manassas is described in Commodore Porter’s report in words that reflect Melville’s indebtedness: “Her only gun went off, and emitting flames through her bow-port, like some huge animal, she gave a plunge and disappeared under the water” (Doc. 511). The details of the Manassas’ death are given by Farragut in his official report (Doc. 522), which Melville borrowed for his fifth stanza:

Compare this stanza with Farragut’s report that “At length the fire slackened, the smoke cleared off, and we saw to our surprise that we were above the Forts, and here and there a rebel gunboat on fire” (Doc. 522).
Melville speaks of the “lewd mob” in New Orleans, held “at bay” by the “moody broadsides, brooding deep,” in a line suggested to him by a statement in the report of General Butler: “I find the city under the dominion of the mob” (Doc. 517). The lines in the same stanza about the religious services,

Derive from Admiral Farragut’s General Order that

Eleven o’clock this morning is the hour appointed for all the officers and crews of the fleet to return thanks to Almighty God for his great goodness and mercy in permitting us to pass through the events of the last two days . . . (Doc. 524).