The Action of 12–17 January 1640 was a naval battle between a Dutch fleet and a combined Spanish-Portuguese fleet during the Eighty Years' War. The battle took place on the Brazilian coast off Pernambuco and was an attempt by a fleet consisting of approximately eighty vessels transporting about 5,000 soldiers under the command of Portuguese Admiral Fernando de Mascarenhas to land reinforcements to bolster the Portuguese militia besieging the city of Recife. On 12 January this fleet was intercepted by a Dutch task force of about forty ships commanded by Willem Loos. The ensuing battle lasted with occasional breaks until the evening of 17 January, when the Spanish and Portuguese fleet retreated and sailed away to the north.