The British shipbuilder Yarrows's design was based on, a prototype destroyer built for the Royal Navy in 1926.[1] On 18 January 1933, a fifth destroyer of the class was ordered from the Lisbon Shipyard, with machinery to be built by Yarrow.[2] Portuguese Dictator António de Oliveira Salazar gave a speech to commemorate the beginning of construction, thanking the navy minister for "choosing to name this unit of our fleet after the river that crosses my town."[3] Dão was launched on 30 July 1934 and commissioned on 5 January 1935.[4]
The Douro-class ships were 323feet long overall, with a beam of 31feet and a draught of 11feet. They displaced 1219LT at standard load and 1563LT at full load.[5]
The Douros were powered by two Parsons-Curtis geared steam turbines, each driving one propeller shaft using steam provided by three Yarrow boilers. The turbines, rated at 33000shp, were intended to give a maximum speed of 36kn. The destroyers carried enough fuel oil to give them a range of 5400nmi at .[5] [6]
Armament was similar to contemporary Royal Navy destroyers, with a gun armament of four 4.7 in (120 mm) Vickers-Armstrong Mk G guns, and three 2-pounder Mk VIII anti-aircraft guns. Two quadruple banks of 21-inch (533 mm) torpedo tubes were carried, while two depth charge throwers and 12 depth charges constituted the ships' anti-submarine armament. Up to 20 mines could be carried. The ships complement was 147 officers and men.[5]
See main article: 1936 Naval Revolt. On 9 September 1936 the crews of the aviso Afonso de Albuquerque and the Dão mutinied while anchored in Lisbon harbour. Opposed to the Salazar dictatorship's support of the Nationalists rebels against the pro-government Republicans in the Spanish Civil War, the sailors confined their officers and declared their solidarity with the Spanish Republic. As the ships were leaving the Tejo estuary they were fired upon by the batteries from the forts and both Afonso de Albuquerque and Dão received direct hits and were grounded.[7] Some of the sailors were killed while trying to flee, but most of the sailors were arrested and sent to the penal colony of Tarrafal in Portuguese Cape Verde. After the mutiny was put down the government claimed that the sailors had prepared to sail to Spain in order to assist the Spanish Republic.[8]
