It mounted seven 10-inch, three 8-inch and twenty-two 32-pounder smoothbore guns and two 8-inch, two 6.5-inch and four 5.82-inch rifled guns.

The exterior batteries were also heavily armed and the garrison numbered 640 men.
The bay was filled with skilfully placed torpedoes, some of them of stupendous size and power and sufficient, it would seem, if properly handled, to destroy all the navies of the world.
All arrangements being completed, the signal for the advance was hoisted at daylight, August 5, 1864.

The Union fleet consisted of 21 wooden vessels and 6 ironclads.

The wooden vessels sailed in pairs, the larger on the starboard, so that if either was disabled the other could carry it along.

Farragut's intention was to lead with the flagship _Hartford_, but he reluctantly allowed the _Brooklyn_ to take that post, since she carried four chase guns to the _Hartford's_ one and was provided with an ingenious apparatus for picking up torpedoes.