By the middle of 1818, the creation of the Chilean Navy was well advanced. And what it might be capable of had been shown inApril, when, hot on the heels ofSan Martin’s victory at Maipú, Lautaro sailed out of Valparaiso with orders to break the blockade. In command was former Royal Navy Lieutenant George O’Brian, supported by three British Lieutenants – James Argent, William Walker and Sam Fawkener – and William Miller who, after Maipú had been promoted to Major and senttoorganise the Chilean Marine Corps. Posing as HMS Amphion, the Lautaro surprised the Spanish frigateEsmeralda on patrol outside the port, ran her bowsprit into the Spaniard’s mizzen rigging and attempted totake her by boarding. Unfortunately for the Chileans, a heavy swell then separated the two ships and the boarding party, led by Captain O’Brian, was overwhelmedand killed.Both sides subsequently claimed a victory; but it was the Chileans who achieved their objective – Esmeralda and her consort, the brig Pezuela, were forced to withdraw and lift the blockade.
Meanwhile, the development of the new navy continued apace with the local purchase of an 18-gun corvette called Chacabuco, and the renaming of the brigAguila as Pueyrredon in honour of the Director of Buenos Aires. The navy also acquired a new senior officer in the person of a 28-year-old army officercalled Manuel Blanco Encalada.