Early in the war, in order to stop the movement of Union Navy ships up the St. Johns River, Confederate Brigadier GeneralJoseph Finnegan established an artillery battery on St. Johns Bluff, on the south side of the river 18 miles downstream from Jacksonville, Florida. This was part of a series of Confederate defensive works that had been constructed near Fort Caroline. But once Union forces had occupied the town of Jacksonville, it became necessary for them to also reduce the enemy batteries along the St. Johns River to consolidate control of the general area.
By midday, the gunboats approached the bluff, while Brannan began landing troops at Mayport Mills. Another Union infantry force landed at Mount Pleasant Creek, about five miles in the rear of the Confederate battery, and began marching overland on October 2. Outmaneuvered, Lieutenant Commander Charles F. Hopkins, the local Confederate commander, abandoned the position after dark. When the gunboats approached the bluff the next day, its guns were silent.