The Confederate States Navy (CSN) was the naval branch of the Confederate States Armed Forces, established by an act of the Confederate States Congress on February 21, 1861. It was responsible for Confederate naval operations during the American Civil War against the United States's Union Navy. The three major tasks of the Confederate States Navy during its existence were the protection of Confederate harbors and coastlines from outside invasion, making the war costly for the United States by attacking its merchant ships worldwide, and running the U.S. blockade by drawing off Union ships in pursuit of Confederate commerce raiders and warships. It was ineffective in these tasks, as the coastal blockade by the United States Navy reduced trade by the South to 5 percent of its pre-war levels. Additionally, the control of inland rivers and coastal navigation by the US Navy forced the south to overload its limited railroads to the point of failure. The surrender of the in Liverpool, England, marked the end of the Civil War and the Confederate Navy's existence. The Confederate Navy could never achieve numerical equality with the Union Navy. It instead sought to take advantage of technological innovation, such as ironclads, submarines, torpedo boats, and naval mines (then known as torpedoes). In February 1861, the Confederate States Navy had 30 vessels, only 14 of which were seaworthy. The opposing Union Navy had 90 vessels. The C. S. Navy eventually grew to 101 ships to meet the rise in naval conflicts and threats to the coast and rivers of the Confederacy. On April 20, 1861, the U.S. was forced to quickly abandon the important Gosport Navy Yard at Portsmouth, Virginia. In their haste, they failed to effectively burn the facility with its large depots of arms, other supplies, and several small vessels. As a result, the Confederacy captured a large supply of much-needed war materials, including heavy cannon, gunpowder, shot, and shell. Of most importance to the Confederacy was the shipyard's dry docks, barely damaged by the departing Union forces.