RMS Alcantara was a Royal Mail Lines ocean liner that was built in Belfast in 1926. She served in the Second World War first as an armed merchant cruiser and then a troop ship. She returned to civilian service in 1948 and was scrapped in 1958. Background In the First World War the Royal Mail Steam Packet Company lost a number of ships to enemy action, including three of its "A-series" passenger liners: , and . After the 1918 Armistice RMSP prioritised the replacement of lost cargo ships, using new refrigerated cargo ships to take a share of the growing trade in frozen meat from South America to the UK. High demand for new merchant ships to replace First World War losses kept shipbuilding prices high, so RMSP Chairman Lord Kylsant deferred ordering any new passenger liners for a few years. However, in 1921 Parliament passed the first of five Trade Facilities Acts, which offered low-interest loans and Government guarantees for repayment. In 1924 Kylsant took advantage of the Act by ordering from Harland and Wolff of Belfast a pair of passenger liners with a speed of . As a diesel-powered motor ship Harland and Wolff launched the new Asturias on 7 July 1925 and completed her in February 1926. Her sister ship Alcantara was launched on 23 September 1926 and completed in February 1927. The latter was named after RMSP's previous Alcantara, which was an armed merchant cruiser in the First World War and had been lost when she and the German armed merchant cruiser sank each other in 1916. The new Alcantara was given the UK official number 148151 and code letters KVQC. When four-letter maritime call signs were introduced in 1934, Asturias was given the call sign GLQR. Each of the two new ships was powered by a pair of eight-cylinder four-stroke double-acting diesel engines built by Harland and Wolff to a Burmeister & Wain design. The engines gave each ship 10,000 ihp or 7,500 bhp, and at the time they were the World's largest motor ships. However, their cruising speed was only , which was less than that of competing ships already on the route between European ports and the South American east coast. This was an embarrassment for Lord Kylsant, who in 1924 had become Chairman of Harland and Wolff in addition to his position as chairman of RMSP. In comparison, Compagnie de Navigation Sud-Atlantique