Union blockade was a naval blockade of Atlantic and Gulf coast of United States by the union navy to stop Confederate states from maritime trade. On 19th April, 1861, President Abraham Lincoln issued the proclamation of blockade against confederate states. The purpose of the blockade was to stop confederation from aiding their war effort through trade and to cripple their economy which heavily relied on it.
Although some historians argue that by proclaiming blockade, Lincoln actually accepted the independent status of Confederacy, but blockade allowed union navy to stop and search vessels attempting to run through it. This was necessary to avoid diplomatic hassles with Great Britain.
Blockade Strategy Board:
In June, 1861 a blockade strategy board was formed under the leadership of Captain Samuel F DuPont. The board was responsible for chalking out a blockade strategy. Union Navy initially had resources only for blocking Atlantic coast. They initially operated from captured Port Royal in South Carolina and used it as a maintenance and repair base as well. The operations were later on extended along the Gulf coast as well. Union navy initially had very few vessels worthy of the purpose.
However, the Department of Navy under the leadership of Secretary of Navy, Gideon Welles, aggressively pursued the expansion of naval fleet. US naval ships patrolling abroad were called back, new vessels were built, captured runners were commissioned in union navy and private boats and ships were purchased. At the time blockade started, Union navy had less than 50 vessels at its disposal for the job. By the time civil war ended, Union navy had a fleet of 671 vessels. Separate squadrons were formed and armed for Atlantic and Gulf coasts under the supervision of their own independent commanders.
The initial success was limited with only one in ten vessels trying to run through the blockade captured. However, as the numerical strength of Union Navy increased, so did the number of captured vessels. By early 1864, one in every three ships trying to run through was being captured. In the last two years only small and fast boats were able to successfully evade union navy. The effectiveness of union blockade forced bigger and slower merchant ships to desist from visiting southern ports. It is estimated that in all, Union navy captured or destroyed close to 1500 vessels trying to run through the blockade during the entire duration of war.
Confederate economy was badly hit by the blockade. Southern economy relied heavily on cotton export for hard cash. Blockade almost completely choked the cotton trade and the exports fell by 95 percent. Confederate states also faced severe difficulty in acquiring medicines, food, luxury items and war material as a result of the blockade. This affected not only the war effort but also the overall public morale in confederate states. Several incidents of food riots were reported across confederate territory.
Confederacy realized the adverse effects, the blockade had on their economy and war effort. Apart from several Naval engagements between Union and Confederate naives, certain novel ideas like use of torpedo boats and a hand powered submarine were also employed unsuccessfully against union vessels. Confederacy was forced to rely on smaller and faster boats for transporting critically essential goods. These vessels were able to run through the blockade but could not carry much load and had to make repeated visits, which meant they were caught or destroyed sooner or later.