The Unsinkable Foundry: How Philadelphia Launched the Naval Blockade That Won the Civil War
Tracing the city’s underappreciated role—from the original Navy Yard to the vast industrial complex on the Delaware—that built and financed the Union’s greatest economic weapon.
For many years, I have enjoyed exploring the old Philadelphia Navy Yard on my bike. It had never occurred to me that this was not the original home of the Philadelphia Naval Yard.
Looking at a military map, in the 1913 book Philadelphia in the Civil War, 1861-1865 by Frank H. Taylor, I was surprised to see the Navy Yard located on Washington Avenue—just blocks from where the Union Volunteer Refreshment Saloon once stood. This whole area was the true logistical engine of the Union war effort.
That got me curious about Philadelphia’s role in supporting the Union Navy. It turns out Philadelphia played an indispensable role in supporting the Naval blockade’s underappreciated role in winning the Civil War.
The naval blockade was strategically vital because it limited the Confederacy’s ability to import crucial resources, thereby denying access to weapons and supplies that the North could produce domestically. This isolation crippled cotton exports, which were the “lifeblood of the agrarian South,” and neutralized the Confederacy’s economic leverage (the “King Cotton” strategy).
The burden of supplying the rapidly expanding wartime navy fell heavily upon the industrial complex along the Delaware River.
The Original Navy Yard: From Southwark to Seapower
The Philadelphia Navy Yard, situated in Southwark (just south of Washington Avenue on the Delaware River), played a significant part in mobilizing resources for the Union war effort. Though the yard had suffered from obsolescence before the war, the outbreak of hostilities drove employment dramatically, swelling the civilian workforce to between 2,500 and 3,000 men at times.
While new construction was part of the mission, the main focus of the Old Navy Yard was the constant repair, refitting, and overhaul of vessels that were continually returning from active duty or distant posts. A demonstration of Philadelphia’s capacity was the construction of the sloop-of-war Tuscarora, which was built in an astonishing 58 days and launched in August 1861. In total, the Navy Yard built approximately eleven new warships during the Civil War.
The Ironclad Revolution: Private Sector Power
Crucially, the technological shift to steam power and ironclad warships required new industrial capabilities that the cramped Old Navy Yard lacked. This led to critical construction contracts being awarded to Philadelphia’s powerful private sector along the Delaware.
The most notable example was the formidable ironclad frigate, the USS New Ironsides, constructed by William Cramp & Sons. Launched in May 1862, this vessel was arguably the most important built at the port for war purposes and proved to be one of the Navy’s most effective ships, showcasing the city’s private industrial might.
The formidable USS New Ironsides, arguably the most important ironclad built in Philadelphia during the war. Constructed by William Cramp & Sons, this vessel was the most conservative of the Navy’s new armored designs but proved to be one of the most effective ships enforcing the blockade off Charleston.
Logistics, Ordnance, and the Spoils of Victory
Beyond shipbuilding, Philadelphia served crucial logistical roles necessary for supporting sustained naval operations.
Ammunition Supply: The Frankford Arsenal was vital for supplying the munitions needed for the blockading squadrons. By 1864, the arsenal was a massive manufacturing center, producing small-arms ammunition essential for enforcing the blockade.
Prize Station: Philadelphia functioned as the northern station for receiving ships and contraband cargo seized in the blockade. The captured Confederate Ram Atlanta (an English blockade runner converted into an ironclad) was loaned to Philadelphia’s Union Committee in 1863 and exhibited at the foot of Washington Avenue to raise funds for war relief, embodying a tangible spoil of naval combat brought directly to the city.
The War’s Financier: Jay Cooke and the $1.4 Billion Lifeline
The vast shipbuilding and supply operations were underwritten by financial giants based in Philadelphia. Banker Jay Cooke, whom the Lincoln administration enlisted, sold $1.4 billion dollars of Union war bonds, ensuring the government had the immense financial capital required to fund the construction and deployment of the Navy, which constantly burned a million dollars a day to fight the war.
In summary, Philadelphia’s contribution to the naval blockade was comprehensive: the city designed and manufactured advanced warships and their machinery, produced the ammunition they fired, maintained them throughout the war, provided the port infrastructure to process the spoils of naval victory, and financed the entire expensive endeavor. The ceaseless roar of the Philadelphia industrial waterfront was, in effect, the mighty engine driving the North’s economic weapon against the South.
