During the War of Northern Aggression, the St Johns River was the diving line between Union occupied territory and Confederate held territory in east Florida. The Union controlled Jacksonville, St Augustine on the Atlantic, and Palatka on the St Johns, which they constantly patrolled with gun boats, from Jacksonville to Lake George, looking for CSA river blockade runners that supplied the Confederacy food, salt, and other goods.
In Palatka, Lola Sanchez, a Confederate spy, supplied Confederate militias, intelligence on the gun boat movements. Sanchez main contact was CSA Capt J J Dickinson of Marion county, whose cavalry raids brought the War to the Union occupiers, and kept central Florida free from Union invasion.
The Union commander at Fort Marion (Castillo de San Marcos) in St Augustine, ordered in May 1864, the gunboats,
USS Columbine and USS Ottawa, to capture or kill Dickinson and his CSA militia.
Sanchez got word to Dickinson, and his 100 man cavalry with a 25 men artillery unit with two small cannons, hid on the west bank at Brown's Landing, south of Palatka.( The field pieces were manufactured by John Pearson's machine shop in Orange Springs on the Oklawaha River. Pearson was another business partner of David Levy Yulee, and a neighbor of Dickinson)
When the Union gunboats appeared, Dickinson let the Columbine proceed down river, then shelled the 52 gun Ottawa, which retreated back to Palatka.
Dickinson then moved his men south to Horse Landing on the St Johns, to lay and wait for the Columbine's return.
A Confederate lookout in a oak tree announced the Columbine's approach, and one of Dickinson's first cannon shell ripped out the gunboat's wheel, and it ran aground. A firefight commenced, 20 Union soldiers killed and 65 taken prisoner.
Dickinson's men unloaded the Columbine of arms, ammunition, food, the paymasters strongbox, and the longboat, which was later used by CSA Sec of War John C Breckinridge and CSA Capt John Taylor Wood in their May 1885 escape from Florida.
After empting the Columbine of all useful items, the gunboat was burned on the banks of the St Johns.
In US history, this is the only event when a cavalry unit sunk an enemy ship.