Originally designed for the Union-Castle Line in 1913, she was ordered from Harland & Wolff but her construction was held up by the First World War. The continuation of the war until late 1918 led Harland & Wolff to subcontract her building to John Brown & Company. Windsor Castle was not completed until 1922. The two ships were the only four-stacked ocean liners built and design for a route other than the transatlantic crossing. She had a capacity of 234 first, 362 second, and 274 third-class passengers. The liner had two masts and two propellers and could reach a top speed of 18 knots. In her refit she was given a raked bow which lengthened her from, to, and had her passenger capacity reduced from 870 to 604. Her top speed was increased to, and her tonnage increased to 19,141 gross register tons.
Windsor Castle set out on her maiden voyage from Southampton to Cape Town in April 1922. This gave the Union-Castle Line the two largest ships on that run to provide an alternating service between England and South Africa. And apart from the comforts, the ship had also been designed with safety in mind. The hull was subdivided into twelve watertight compartments and a double bottom. Furthermore, Windsor Castle was equipped with many lifeboats, with room for the ship’s total capacity of passengers. Just aft of the fourth funnel, the ship had a pair of gantry davits (like those carried on) alone capable of handling twelve boats.
During the 1930s, Windsor Castle and Arundel Castle were given refits to make them look more modern. This included reducing their funnels from four to two, with new Babcock-Johnson boilers,[1] and they both were given raked, more modern bows, which slightly increased their length. Also removed were the ships' large gantry-like davits capable of carrying six lifeboats each, which were replaced with the much more common Welin davits featured on liners such as .
Requisitioned as a troopship in the Second World War, she was bombed west of Ireland in 1941 but the bomb never exploded and she reached port. She was used for transatlantic trooping from Canada and the USA in 1942. in 1943, Windsor Castle was sunk by a torpedo launched from a German aircraft while in the Mediterranean Sea as part of convoy KMF-11.[2] She was hit at 2:30 am but did not sink until 5:25 pm, going down stern first, WNW of Algiers, Algeria. Only one crewman was killed, 2,699 troops and 289 crew were rescued by the destroyers,, and .