Question: The Battle of Vuelta de Obligado was part of a larger naval blockade that lasted how long?

Admiral Sir Astley Cooper Key (18 January 1821 – 3 March 1888) was a Royal Navy officer.  As a junior officer he saw action at the Battle of Vuelta de Obligado in November 1845 during the Anglo-French blockade of the Río de la Plata and took part at the Battle of Bomarsund in August 1854 and the Bombardment of Sveaborg in August 1855 during the Crimean War.  He also went ashore with the naval brigade to take part in the Battle of Canton in December 1857 during the Second Opium War.  He later commanded a specially-formed Baltic Fleet created in February 1878 to intimidate Russia from entering Constantinople during the closing stages of the Russo-Turkish War.  He became First Naval Lord in August 1879 in which role he was primarily interested in administration and technology rather than strategy: he kept the cost of running the Navy within budgets, sanctioned the construction of six Admiral class battleships and ensured the Navy was properly prepared for the Panjdeh Incident in 1885 when Russian forces seized Afghan territory at Panjdeh. <SEP> The National Sovereignty Day (Spanish: "Día de la Soberanía Nacional" ) is a national public holiday of Argentina, celebrated during November 28.  It commemorates the Battle of Vuelta de Obligado, when a small Argentine army stood against an Anglo-French navy that broke into the Paraná River on November 20, 1845, against the will of the Argentine Confederation.  Although the battle itself ended with an Argentine defeat, the losses of Britain and France in the whole military campaign were so high that both countries were forced to the bargaining table and signed a treaty with Juan Manuel de Rosas.  The day was enacted as a national observance in 1974, following a request from the revisionist historian José María Rosa, and promoted into a national holiday in 2010. <SEP> The naval Battle of Vuelta de Obligado took place on the waters of the Paraná River on 20 November 1845, between the Argentine Confederation, under the leadership of Juan Manuel de Rosas, and a combined Anglo-French fleet.  The action was part of the larger Anglo-French blockade of the Río de la Plata.  Although the attacking forces broke through the Argentine naval defenses and overran the land defenses, the battle proved that foreign ships could not safely navigate Argentine internal waters against its government's wishes.  The battle also changed political feeling in South America, increasing support for Rosas and his government. <SEP>  It was imposed in 1845 to support the Colorado Party in the Uruguayan Civil War and closed Buenos Aires to naval commerce.  The Anglo-French navy trespassed into the internal waters of Argentina, in order to sell their products, as Rosas maintained a protectionist policy to improve the weak Argentine economy.  Eventually both Britain and France gave in, signing treaties in 1849 (Britain) and 1850 (France) acknowledging the Argentine sovereignty over its rivers. The Anglo-French blockade of the Río de la Plata was a five-year-long naval blockade imposed by France and Britain on the Argentine Confederation ruled by Juan Manuel de Rosas.