The Story So Far: Civil War Naval Events Leading Up to John William Denny’s Diary

By Nick Wieman
HRNM Educator

John William Denny at age 84 (Descendants of Henry Denny)

John William Denny (May 16, 1840 – September 15, 1930), a native of Newark, New Jersey, moved to Jacksonville, Florida for work when he was 17. In April 1862, he enlisted in the Union Navy (likely through nearby Fort Clinch, which had been abandoned by the Confederates the previous March) and was appointed as a Captain’s Clerk to Lieutenant Daniel Ammen, captain of USS Seneca. He followed Lieutenant Ammen to USS Sebago and USS Patapsco, transferred briefly to USS Wabash to serve under Commander Christopher Rodgers, then finished his naval career (as far as we know) as clerk to Major Anthony Ten Eyck at Hilton Head, South Carolina.

According to family history, after the war, he found work as a county treasurer in Columbia, South Carolina, before returning to Newark in 1872. After years of working as a bookkeeper for the family coal and wood business, he would be hired by the James A. Bannister Shoe Manufacturing Company in 1890, serving as the company’s Vice President and Treasurer, a position he would hold until his retirement in 1924. This blog will cover the events leading up to June 12, 1862, the day that Denny began keeping a diary, with successive blogs covering topics that Denny mentions in the diary proper.

Following the bombardment of Fort Sumter, marking the official beginning of the Civil War, General Winfield Scott proposed a total naval blockade of southern ports, cutting off the Confederacy from foreign trade and the South’s ability to sustain the war economically. It was dubbed the “Anaconda Plan” by critics for the imagery of the blockade encircling the South as the anaconda constricts its prey. The Blockade Strategy Board, led by Flag Officer Samuel Francis DuPont, was in charge of translating this lofty goal into action.

Anaconda Plan cartoon (Wikipedia)

Blockading almost 3,000 miles of coastline called for a fleet of small, light-drafted gunboats that were also fully seaworthy, and there was nothing currently in the Union Navy that was capable of fulfilling this task. Modifying a design he had made for the Imperial Russian Navy, Chief Engineer Benjamin F. Isherwood oversaw the construction of the Unadilla-class gunboat, also known as the “90-day gunboat” for how quickly the first four boats were completed from the contract being signed to the first ship, Unadilla, commissioned 93 days later. USS Seneca was one of 23 Unadilla-class gunboats, commissioned on October 14, 1861.

USS Seneca (Wikipedia)

Even if the Union Navy had enough ships to enforce the blockade, it could not feasibly maintain the blockade relying on northern ports for resupply, maintenance, and refueling. For that reason, one of the first offensives that the Union Navy took was the seizure of southern ports to act as reliable bases for the blockade squadrons. Port Royal Sound, part of the Sea Islands between Charleston and Savannah, was chosen for its geographic proximity to the two major Confederate cities and marshy waters hampering any Confederate counterattack. The Sound was protected by Confederate forces at Fort Walker on Hilton Head Island, Fort Beauregard across the Sound on Phillips Island, and a squadron of four small gunboats under Josiah Tatnall (future commander of CSS Virginia). General Thomas Drayton and Colonel Stephen Elliot Jr. commanded forces at Fort Walker and Fort Beauregard respectively.

On November 7, 1861, around 9:30 A.M., a fleet under Flag Officer Samuel DuPont (including USS Seneca) moved into action. The plan was for the fleet to steam right down the middle of the channel, staying in motion while firing on both forts. Turning in succession about midway through the channel, one column of ships led by DuPont aboard USS Wabash would double back along the shore of Hilton Head Island, laying further fire on the more heavily defended Fort Walker, while the other ships would provide cover against the Confederate gunboats.

Port Royal plan of attack (NHHC)

When it came time for the ships to execute the turn-in-succession, however, Sylvanus Godon of USS Mohican took the initiative to break away from the line and enfilade Fort Walker, confusing others in the line into breaking off from Wabash and taking position in the fort’s “blind spot.” While most of the ships continued to concentrate their fire on either fort, USS Seneca charged directly at the Confederate gunboat squadron, which had thus far been prevented from joining the battle by the ships providing cover. Seneca pursued Tattnall’s squadron for over two miles up Skull Creek before the Confederates managed to escape.

Bombardment and Capture of Forts Walker and Beauregard (Mariners' Museum)

General Drayton gave the order to evacuate around 2:00 P.M., the gunners at Fort Walker having depleted almost all of their gunpowder, and having had many of their guns disabled. To add insult to Drayton’s injury specifically, the late-arriving USS Pocahontas had joined the bombardment, a ship commanded by his own brother, Percival Drayton. Captain John Rodgers of Wabash led a landing party ashore under a flag of truce only to find the fort abandoned, and he raised the Stars and Stripes over the fort. The Confederates abandoned Fort Beauregard when Colonel Elliot heard Walker’s guns fall silent and cheers erupt from the Union fleet; John Ammen of USS Seneca had the honors of raising the flag.

Raising the flag over Port Royal (Wikipedia)

The capture of Port Royal allowed the Union to seize control of the rest of the Sea Islands, providing the Atlantic Blockading Squadron a forward operating base in the heart of the Confederacy for all blockade operations from Hampton Roads to Key West. The capture of these islands would also become the site of the “Port Royal Experiment,” a prelude to Reconstruction where former enslaved people received education and worked the land abandoned by their former enslavers.

While Denny enlisted after the Battle of Port Royal, his naval career was shaped by its consequences. Rather than naval warfare defined by opposing warships fighting each other head on, this naval campaign would be characterized by Union ships standing watch, on the lookout for Confederate cargo vessels whose greatest weapon was their speed and stealth. Future entries in this series will examine the life of John William Denny, Captain’s Clerk, as his diary provides a glimpse into not only blockade duty, but other aspects of the Civil War that intersected with his professional and personal life.