Jacksonville was first occupied by Federal troops March 12, 1862, for the purpose of giving aid and comfort to the Union sympathizers of the region. The town was evacuated in less than a month, but a Federal blockade of the St. Johns River was maintained by gunboats of Admiral Du Pont’s South Atlantic squadron with their station at a steam sawmill called Mayport Mills, a settlement that grew into the present town of Mayport and from which the name Mayport is derived. The gunboats patrolled the river at will and frequently went up to Jacksonville and beyond to reconnoiter. To prevent this Gen. Joseph Finegan, commander of the Confederate forces in this portion of the state, decided to fortify St. Johns Bluff on the south side of the river some four miles above Mayport Mills as the river runs. The situation was an ideal one for the purpose-a steep promontory rising from the river’s edge to an elevation of more than 70 feet, the channel of the river running close inshore at that point.
Davis, T. Frederick
"Engagements at St. Johns Bluff St. Johns River, September-October, 1862,"
Florida Historical Quarterly: Vol. 15:
2, Article 3.
Available at: https://stars.library.ucf.edu/fhq/vol15/iss2/3