John Dimitry , A. M., Confederate Military History, a library of Confederate States Military History: Volume 10.1, Louisiana
Clement Anselm Evans, Ed.

[57] Nor did it consider that the city had not then surrendered; that the authority of the United States had not been acknowledged by the citizens; and that, technically, no crime had been committed against the power which, in a city in rebellion, had as yet no official existence. Flag-officer Farragut's fleet was abreast the city. It was fully capable of enforcing, at a moment's notice, its surrender. That the city was still Confederate, even with the Union fleet in sight, and that it remained as such from April 27th (inclusive) to April 29th, are made as clear as the fact that the surrender had not absolutely been accomplished. Mumford was still a citizen of a Confederate city, in which Confederates, having evacuated the city with their army, had not yet abdicated their civil authority. On April 28th Mayor Monroe had no intimation that ‘it was by your (Farragut's) orders, that the United States flag was attempted to be hoisted upon certain of our public edifices.’ On April 29th, two days after Mumford's act, Flag-officer Farragut addressed the following communication to Mayor Monroe. It was delivered to the mayor by two naval officers from the fleet:

U. S. Flag-ship Hartford, At anchor off the city of New Orleans, April 29, 1862.
His Honor, the Mayor of the City of New Orleans,

Sir: The forts, Saint Philip and Jackson, having surrendered and all the military defenses of the city being either captured or abandoned, you are required, as the sole representative of any supposed authority in the city, to haul down and repress every ensign and symbol of government, whether State or Confederate, except that of the United States., I am about to raise the flag of the United States upon the custom house, and you will see that it is respected with all the civil power of the city. I have the honor to be, very respectfully,

Your obedient servant,

D. G. Farragut, Flag-officer Western Gulf Blockading Squadron.

A flag is the symbol of authority. In the final demand of surrender of all authority on the part of the authorities