In August 1920, the NDL made an agency agreement with the U.S. Mail Steamship Co. (beginning in 1921, United States Lines). This made it possible to resume transatlantic service from Bremerhaven to New York with the former "Rhein", now sailing under the US flag as the "Susquehanna". The unfinished "Columbus" had been awarded to Great Britain after the war and was bought in 1920 by White Star, which had lost significant tonnage in the war and also wished to make up for the pre-war loss of the "Titanic". However, work at Danzig proceeded very slowly. Finally in autumn 1921 the so-called Columbus Agreement was reached, under which the German government and NDL undertook to facilitate rapid completion of the "Columbus" in exchange for the British government returning ownership to the NDL of six smaller ships which had spent the war years in South America: the postal steamers "Seydlitz" and "Yorck", the "Gotha", and the freighters "Göttingen", "Westfalen" and "Holstein". The company also began to build new freighters and passenger ships and to buy back other ships. In late 1921, service to South America was resumed with the "Seydlitz", and in early 1922, East Asian service with the "Westfalen". On 12 February 1922, service to New York with NDL's own ships resumed with "Seydlitz". The other ship of the Columbus class, the former "Hindenburg", was completed in 1924 and named "Columbus"; she was placed in scheduled transatlantic passenger service.