Does anybody know what unit this may have been?
From a June 18, 1863, report from C.A. Dana to Sec. o' War Stanton.
"Fifteenth Army Corps, who witnessed the late battle at Millikenís Bend, certified in an official statement that the rebels carried a black flag bearing a deathís head and cross-bones."
There is a report that the 1st Louisiana Cavalry Regiment (Colonel John Scott's regiment) commanded by Captain Joseph Benjamin used a flag of this description.