 The new unit achieved some success before being routed by Admiral Brown in the battle of Costa Brava, on the Paraná River.After this, the war simply became a siege of Montevideo, with Argentina and the Blancos in control of the sea, but the supply to the port was granted by Britain.With the war in Uruguay over and Rosas overthrown in Argentina, Coe was appointed by Justo José de Urquiza commander of the Confederation fleet which blockaded the city in the after the Province seceded from the central government, becoming the State of Buenos Aires in September 1852.