The political complexities surrounding war between Argentina and Uruguay in the mid-1840s are impossible to sketch in a short article. British and French interest in the situation focussed on protection of commercial interests in Uruguay and on keeping navigation of the Parana River open to commercial traffic. This huge river, navigable by sea-going vessels of the time for much of its length, leads into the very heart of South America.
View of the boom from the Argentinian batteries on the cliff south of the river
In mid-1845 Argentina had closed the river by means of a boom and shore batteries at La Vuelta de Obligado, some 120 mile NNW of Buenos Aires. At this point the river is 700 metres wide and a tight turn (vuelta in Spanish) makes navigation difficult. British merchant shipping was trapped upstream and other ships, 92 in total, carrying manufactured goods, were unable to move upstream. At this period of British commercial dominance the challenge was irresistible, as it also was for the French.
The Argentine boom extended completely across the river and consisted of 24 vessels linked by three strong metal chains. Only three of these vessels were Argentinian naval units and the remainder were requisitioned. Four artillery batteries with 30 cannons in total, a mix of 8, 10, 12 and 20-pounders, were dug in on a cliff that rose from 100 to 600 feet on the southern bank, and supported by some 2,000 entrenched troops. A small brigantine, the Republicano, and two small gunboats, the Restaurador and the Lagos, were also available to protect the boom.
The combined British-French force that moved upriver totalled eleven warships, six of them of the Royal Navy. Eight of the vessels were sailing craft but the most powerful were three steam paddlers: HMS Gorgon, HMS Firebrand and the French Fulton. Steam power in warfare still a novelty and these vessels represented contemporary cutting-edge technology.
HMS Gorgon – by Sir Oswald Walters Brierly
The Gorgon, which had already seen action in the bombardment of Acre in 1840, can be considered representative of the type. Of wooden construction and of 1,610 tons, she was classed as a sloop. Her length was 152 feet along the keel and her 800 hp 2-cylinder direct-acting steam engine drove two enormous 27 foot diameter paddle wheels – and obvious point of vulnerability in battle. Though capable of 9.5 knots under steam considerations of coal supply demanded that she also carry an auxiliary sailing rig. Her armament was impressive for her size – two pivot-mounted 10-inch guns, two 68-pounders and two 42-pounder carronades. In addition the British ships carried Congreave rockets, probably 24-pounders, which, due to their high trajectories, were to prove very useful for attacking the Argentinian positions on the cliffs.
The Argentinian batteries under rocket bombardment