Sea Foam was assigned to the Mortar Flotilla which was established early in 1862 to support Flag Officer David Farragut's New Orleans, Louisiana, campaign.

Then, at midnight on the night of 23 and 24 April, she opened fire to join the bombardment which preceded Farragut's dash up river past the forts.

However, the Flag Officer was delayed by operations on the Mississippi and, after learning of the strength of the Confederate works at Vicksburg, recalled Porter and the mortar vessels.

For the next year, the brig, badly hampered by yellow fever, remained on the Mississippi River supporting the operations of the West Gulf Blockading Squadron.

Restored to fighting trim, Sea Foam was recommissioned at Boston on 1 August 1864 and assigned to the South Atlantic Blockading Squadron.