While in command of U-53 her first captain Hans Rose became the 5th ranked German submarine ace of World War I sinking USS Jacob Jones and 87 merchant ships for a total of 224,314 gross register tons (GRT).

[5][6] After sea trials found no defects the submarine passed through the Kiel Canal on 30 May to reach the naval base at Helgoland the following day.

[5] While U-53 was in Wilhelmshaven having its steering gear repaired and with most of its crew away on leave, Rose was called on 3 September 1916 to office of Fregattenkapitän Hermann Baur, commander of the U-boat fleet on the Hamburg.

However with this amount of fuel on board and the necessary provisions the submarine’s buoyancy would be reduced in half and it would sit 400 mm lower in the water, which would badly impact on its sea-worthiness on the outward journey.

After deliberating for two days as to whether the report was true or the Bremen was merely late Rose decided to continue with his original orders to Newport, Rhode Island rather than divert to attack shipping at Halifax.

The 4,224 GRT Norwegian steamship Christian Knutsen with a cargo of diesel oil for London was stopped at 08:03 and torpedoed at 09:53 after the crew had abandoned ship.

After sinking five ships in 17 days with no loss of life Rose set a homeward course via the Gulf Stream and evaded three British destroyers sent from Canada to intercept him.

After a soothing speech by Sir Edward Grey, these complaints were calmed when he pointed out that the US ships had no legal right to interfere with these attacks and had done all they could to rescue the sailors in the water.

In the summer of 1917 German naval artist Claus Bergen accompanied U-53 on an Atlantic patrol, resulting in a series of well-known paintings.

[14] On 3 February 1917 U-53 captured and scuttled SS Housatonic about 20 nautical miles (37 km) southwest of Bishop Rock, Isles of Scilly.

[20] On December 6, 1917, Rose torpedoed and sank USS Jacob Jones, the first American destroyer lost in the First World War.

[citation needed] On 8 July 1918 while off the Norwegian coast and two days out from its base at Helgoland U-53 answered a distress call from U-86 which had hit a mine and as a result had lost all of its diesel fuel.

[23] Under von Schrader U-53 operated primarily within the English Channel after this, attacking Allied and neutral vessels, sinking ten ships of 1,782 tons with U-53 before the armistice on 11 November.

[24] The naval historian Mark Chirnside carried out research which concluded that U-53 fired a torpedo at the liner RMS Olympic on 4 September 1918, in the English Channel.