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German liner Imperator at anchor, c. 1913, with the grandiose bow eagle of the Hapag company still in place.
|Owner:||Hamburg America Line|
|Port of registry:||Hamburg|
|Launched:||23 May 1912|
|Christened:||24 May 1913|
|Completed:||June 1913 at Hamburg, Germany|
|Maiden voyage:||11 June 1913, Cuxhaven to New York|
|Fate:||War prize to the United States|
|Acquired:||by the Navy 5 May 1919 at Brest, France|
|Commissioned:||5 May 1919 USS Imperator at Brest, France|
|Decommissioned:||24 November 1919 at New York City|
|Fate:||Sold to the Cunard Line and renamed Berengaria|
|Fate:||Scrapped between 1939–1946|
|Class and type:||Imperator-class ocean liner|
|Length:||906 ft (276 m)|
|Beam:||98 ft 3 in (29.95 m)|
|Draught:||35 ft 2 in (10.72 m)|
|Installed power:||Steam generated at 265 psi by 46 watertube boilers of Vulcan Yarrow design, originally coal burning, later converted to oil fired in 1921.|
|Propulsion:||4 steam turbines AEG-Vulcan / Parsons direct drive on four shafts, total of 60,000 shp (45,000 kW)|
|Speed:||24 kn (44 km/h; 28 mph) max|
SS Imperator was an ocean liner built for the Hamburg America Line ( Hamburg Amerikanische Paketfahrt Aktien Gesellschaft, or HAPAG), launched in 1912. At the time of her completion in June 1913, she was the largest passenger ship in the world by gross tonnage, surpassing Titanic's sister ship, RMS Olympic. Upon launch, he also surpassed the recently sunk RMS Titanic and the Olympic by 24 ft (7.3 m) in length. Although in German and English that all ships are usually referred to as feminine, during his Hamburg American Line career, the ship was referred to as masculine at the special request of Kaiser Wilhelm II.
During World War I, the ship remained in port in Hamburg. After the war, he was briefly commissioned into the United States Navy as USS Imperator (ID-4080) and employed as a transport, returning American troops from Europe. Following his service with the U.S. Navy, Imperator was handed over to Britain's Cunard Line as part of war reparations where he sailed as the flagship RMS Berengaria for the final decade of his career.
The first plates of his keel were laid in 1910 at the Vulcan Shipyards in Hamburg, Germany, and made his maiden voyage in 1913. At 52,117 gross tons, Imperator was the largest ship in the world until Vaterland sailed in May 1914. 
Before his launch on 23 May 1912, Cunard announced that their new ship, RMS Aquitania, which was under construction at the time at the John Brown shipyards in Glasgow, would be longer by one foot. There was chagrin in Hamburg. Several weeks later, she was fitted with an imposing bronze eagle figurehead, created by Professor Bruno Kruse of Berlin, which adorned his forepeak with a banner emblazoned with HAPAG's motto Mein Feld ist die Welt (My field is the world); this increased Imperator's length to surpass Aquitania. The eagle's wings were later torn off in an Atlantic storm during the 1914 season, after which it was removed and replaced with gold scroll-work similar to that on his stern.
On his initial sea trials, the ship ran aground on the Elbe river due to insufficient dredging and a flash fire in the engine room which resulted in eight crewmen being taken to hospital. On her official trials, he suffered overheating of the turbines and some stability issues were discovered. The trials were therefore abandoned and the builders were called in to carry out emergency work. At the same time, the overnight cruise for the Kaiser was cancelled; it was eventually carried out in July that year.
Imperator left on his maiden voyage on Wednesday, 11 June 1913, with Commodore Hans Ruser in command and Hamburg-Amerika appointing four other captains for the journey to make sure that everything went smoothly. On the way, she stopped at Southampton and Cherbourg before proceeding across the Atlantic to New York, arriving on 19 June 1913. On board were 4,986, consisting of 859 first-class passengers, 647 second-class passengers, 648 third-class passengers, 1,495 in the steerage, and 1,332 crew.  The ship returned to Europe from Hoboken, New Jersey on 25 June 1913. 
On his first arrival the harbour pilot assigned to bring her into the Ambrose channel, Captain George Seeth, noted that the ship listed from side to side when the helm made changes to the ship's direction. He was soon nicknamed "Limperator".
In October 1913, Imperator returned to the Vulkan shipyard to facilitate drastic work to improve her handling and stability, as it had been discovered that her centre of gravity was too high (see metacentric height). To correct the problem, the marble bathroom suites in first class were removed and heavy furniture was replaced with lightweight wicker cane. The ship's funnels were reduced in height by 9.8 ft (3 m). Finally, 2,000 tons of cement was poured into the ship's double bottom as ballast. This work cost £200,000, which had to be borne by the shipyard as part of their five-year warranty to the shipowners. At the same time, an advanced fire sprinkler system was fitted throughout the ship, as several fires had occurred on board since the vessel had entered service.
During the 1914 refit of Imperator, Commodore Ruser handed over command of the ship to Captain Theo Kier and left to take command of the new larger flagship Vaterland, which was nearing completion. Imperator returned to service on 11 March, arriving at New York five days later on the 19th.
Among his luxurious features, Imperator introduced a two-deck-high, Pompeiian-style swimming pool for his first-class passengers.
In August 1914, as World War I began, she was laid up at Hamburg and remained inactive for more than four years, falling into dilapidation. Following the Armistice of 11 November 1918, Imperator was taken over by the Allied Food Shipping and Finance Agreement, and allocated to the United States for temporary use as a transport alongside Vaterland, which was now renamed SS Leviathan and bringing American service personnel home from France. 
She was commissioned as USS Imperator (ID-4080) in early May 1919. After embarking 2,100 American troops and 1,100 passengers, Imperator departed Brest, France on 15 May 1919, arriving at New York City one week later. Operating with the Cruiser and Transport Force from 3 June to 10 August, she made three cruises from New York to Brest, returning over 25,000 troops, nurses, and civilians to the United States.
While en route to New York City 17 June, Imperator assisted the French cruiser Jeanne d'Arc, which had broken down in the Atlantic Ocean. The President of Brazil was on board Jeanne d'Arc and Imperator received him and his party for transport to the United States, arriving there several days later.
Decommissioned at Hoboken, New Jersey in early 1919, Imperator was transferred to the British Shipping Controller on 20 September, and it was decided that she would be operated by Cunard. Captain Charles A. Smith and a full crew was sent out to New York on Carmania by her new operators and the official handover from the American board of shipping to Cunard took place on 24 November. Imperator was then transferred to Cunard's pier 54 for Cunard service.
The ship arrived at Southampton on Sunday 10 December 1919 and then proceeded to Liverpool for what was planned to be a quick overhaul (she was scheduled to leave on her first voyage for her new owners on 10 January 1920). However, upon inspection, ship was found to be in a poor condition. During dry-docking on 6 January, it was found that the ship's rudder had a piece missing and her propellers were suffering from erosion on their leading edges. These issues were attended to while the ship was refurnished with items borrowed from the Cunard vessels Transylvania and Carmania. 
Due to the extent of the work that had to be carried out, Imperator remained at Liverpool until 21 February and during this time the company's annual dinner was held on board, before the ship returned to service on the North Atlantic.  On 2 March 1920, the ship left New York, taking nine days to reach Southampton. During the voyage, Imperator developed a severe list which was found to be caused by a faulty ash ejector. Cunard decided that the ship was in need of a major overhaul and she was withdrawn from service. 
The ship was renamed after the English queen Berengaria of Navarre. Many Cunard ships had been named for parts of the Roman Empire and had names that ended in "ia". Like several other Cunard ships, RMS Berengaria kept the "ia" ending to her name but was not named after a province of the ancient world.
Sir Arthur Rostron of the RMS Titanic passenger rescue fame and former captain of Carpathia took command of Berengaria in July 1920. The following year both Berengaria and Aquitania were sent to Armstrong Whitworth shipyards to be converted from coal firing to oil. 
In September 1925, a security alert at sea was triggered when the Cunard company offices in New York received a message stating there was a bomb aboard Berengaria; the vessel was then 1,200 miles out from New York, bound for Southampton. The ship was searched although the passengers and most of the crew were not informed as to the reason. A fire drill was held just before the supposed time of detonation, so passengers could be placed close to their lifeboat stations without arousing suspicion. The bomb threat failed to materialize. 
On 11 May 1932, Berengaria ran aground in the Solent. She was refloated an hour later.  In May 1934, Berengaria was again in the headlines when she ran aground on the mud banks at Calshot on the Solent. She was pulled free from the mud by four tugs from Southampton. The vessel suffered no damage and the incident did not affect her sailing schedule.  
Despite her German heritage, Berengaria served as flagship of the Cunard fleet until she was replaced by her sister ship, RMS Majestic (also German: ex- SS Bismarck), in 1934 after the merger of Cunard with White Star Line.  In later years, Berengaria was used for discounted Prohibition-dodging cruises, which earned her the jocular nickname "Bargain-area". 
Toward the end of her service life, she suffered several electrical fires caused by aging wiring, and Cunard-White Star opted to retire her in 1938. She was sold to Sir John Jarvis, who also purchased Olympic, to provide work for his local region.  She sailed for the River Tyne under the command of Captain George Gibbons and was scrapped down to the waterline. Due to the size of the vessel and the outbreak of the Second World War, final demolition took place only in 1946.
- "Imperator". AtlanticLiners.com. 2009. Retrieved 2009-01-11.
"Big Ship, Nearing New York, Behaves Admirably on Trip".
The New York Times via
Marconi Wireless. 16 September 1913. Retrieved 2009-11-17.
Never before were there so many persons on one ship as are on the Imperator. The exact number is 4,986, consisting of 859 first-class passengers, 647 second-class, 648 third-class, 1,495 in the steerage, and 1,332 in the crew.
"Imperator Starts Return Trip To-day. Begins First Voyage to the Eastward with More Than 1,000 in Cabins". New York Times. 15 June 1913. Retrieved 2009-11-17.
The new Hamburg-American liner Imperator, the world's biggest transatlantic steamship, will sail on her first eastward voyage across the Atlantic at 11 o'clock this morning. The great liner when she backs out from her Hoboken berth into the river will have on board more than 1,000 cabin passengers, of whom over 600 will be first cabin.
- "SS Imperator / RMS Berengaria". Ocean-Liners.com. 2009. Archived from the original on 31 January 2009. Retrieved 11 January 2009.
- "Bomb hoax on the liner Berengaria". The Manchester Guardian. 25 September 1925. Retrieved 10 October 2011.
- "The Berengaria aground". The Times (46131). London. 12 May 1932. col C, p. 11.
- "Berengaria". Chris' Cunard Page. Retrieved 2010-02-17.
- Layton, J. Kent (2013). "Imperator/Berengaria". The Edwardian Superliners: A Trio of Trios (2nd ed.). Amberley.
- This article incorporates text from the public domain Dictionary of American Naval Fighting Ships. The entry can be found here.
- The Hamburg-American Company's New 50,000-Ton Liner (International Marine Engineering feature article, August 1912, pp. 301–305, with launch photos & engineering details.)
- SS Imperator / RMS Berengaria
- Atlantic Liners: A Trio of Trios, by J. Kent Layton
- Ocean Liners, by Oliver le Goff
- The Beautiful and Damned, by F. Scott Fitzgerald
- Imperator/Berengaria, by Les Streater
|Wikimedia Commons has media related to Imperator (ship, 1913).|
- S.S. Imperator at Flickr via Library of Congress
- S.S. Imperator (German Passenger Liner, 1913) – Served as USS Imperator (ID # 4080) in 1919. – Later the British Passenger Liner Berengaria
- USS Imperator (ID # 4080), 1919–1919.
- Photo gallery of Imperator at NavSource Naval History
- RMS Berengaria / SS Imperator on Facebook
- Imperator / Berengaria Home at Atlantic Liners.
- Ship's page at ocean-liners.com
- The Ultimate Imperator
- Chris' Cunard Page
- Final sailing to Sir John Jarvis's scrapyard; Jarow