and two 150 mm deck guns), successfully covering the escape of San Miguel. After being able to sustain a disproportionate combat for several hours, Augusto de Castilho was destroyed and sunk, with the death of its captain and several other crew members. Another wartime mission for the Navy was the transportation and the convoying of the Portuguese expeditionary troops sent to fight in the European Western Front and in the Southern African campaigns. More than 56,000 men of the Portuguese Expeditionary Corps and of the Portuguese Independent Heavy Artillery Corps were transported to France, more than 15,000 men to Angola and more than 17,000 to Mozambique. Smaller military contingents were also transported to other Portuguese island and overseas territories. The Portuguese Merchant Marine also made a major contribution for the war effort of Portugal, either with their vessels and personnel mobilized to serve as part of the Portuguese Navy, either by their own, transporting troops and supplies under the constant danger of U-boat, naval mine and merchant raider attacks. From 1916 to 1918, 115 Portuguese merchant ships were sunk by U-boats, with the loss of 120 members of their crews. Interwar period After the end of World War I, Portugal continued the Douro-class destroyer and the Beira-class gunship programs, building two additional units of the previous and three units of the latter. As a war compensation, the Portuguese Navy received six Austrian-Hungarian Tb 82 F-class torpedo boats, with only four of these being commissioned. The Navy also acquired two British Arabis-class sloops, that were commissioned as cruisers. In 1922, the Portuguese naval officers Sacadura Cabral and Gago Coutinho made the first aerial crossing of the South Atlantic. They left the Lisbon Naval Air Station in Bom Sucesso, on 30 March, in a Fairey III-D MkII seaplane of the navy, specifically outfitted for the journey. The aircraft was equipped with an artificial horizon for aeronautical use, a revolutionary own invention of Gago Coutinho. They arrived on the Brazilian Saint Peter and Saint Paul Archipelago on 17 April and ended the journey in Rio de Janeiro on the June, 17. The Interwar period sees the start of the construction of a new naval base and a large arsenal at the Alfeite, in the southern bank of the Tagus estuary. The facilities at the Alfeite were intended replace the Lisbon Navy Arsenal and the several small stations dispersed throughout Lisbon and the Tagus