The contract to build Aquitania went to John Brown & Co. Aquitania was launched on April 21 by the Countess of Derby in front of a crowd of over 101,000 people. Cunard made sure that lifeboat accommodation was provided for all those on board, learning from the terrible Titanic disaster. It was announced in February 1914 that Captain William Turner would be the first master of the ship.

The Aquitania's passenger accommodation was superior to anything seen on the North Atlantic before. The first class drawing room was decorated in the Adam style, copied from certain features in Lansdowne House in London. The walls were adorned with prints of English seaports and portraits of Royalty and prominent people of the day.

The smoking room was modeled on Greenwich Hospital with oak paneling and beams, the restaurant was decorated in Louis 14th style and the ships grill room was decorated in Jacobean style. With public rooms of this standard and passenger cabins superior to those on previous Cunarders it was no surprise that the Aquitania became one of the best known, and most popular Cunard liners.

Aquitania's maiden voyage from Liverpool to New York begun on May 30th, 1914, thus starting a very successful career. The ship made three voyages to New York before the outbreak of World War One. Aquitania was then requisitioned by the British Government to serve as an armed merchant cruiser and was converted for this role in Liverpool. It was then commissioned into the Royal Navy on 7th August and its first assignment was to patrol the Western Approaches, returning to the Mersey on August 16th.

On her next voyage in this role, Aquitania collided with the Leyland ship "Canadian" on August 22nd, whilst in thick fog, and had to return to Liverpool. The subsequent enquiry decided that Aquitania was far too large to be used as an armed merchant cruiser, a fact that in hindsight was painfully obvious. Repair work on the ship was completed by the latter part of 1914. On 18th June 1915 she was again requisitioned by the Government, this time to serve as a troopship and assist in the infamous Gallipoli campaign. On 25th June she left Liverpool with a full complement of over 5,000 troops on board. After three voyages as a troop transport the ship was converted for use as a hospital vessel and served this role during December 1915 and January 1916.

On 10th April 1916, "Ship Beautiful" ended British Government service and was reconditioned by Harland & Wolff in order to return to Cunard service. When this was almost complete the Government was forced to requisition the Aquitania once again to serve as a hospital ship in November 1916. The ship served in the Mediterranean for the rest of the year and was then anchored in the Solent for the whole of 1917. The entry of the USA into the war in December 1917 brought the ship back into service to transport the American Expeditionary Force. After the war it was also used in the repatriation of Canadian troops.

From November 1919 until June 1920 the ship underwent an extensive refit at Armstrong Whitworth & Co on the Tyne. Whilst this was being done the opportunity was taken to convert the ship to oil burning, as opposed to coal, thus eliminating the need of the "black gang" of stokers. After trials north of Scotland, she made her next voyage from Liverpool to New York on 17th July. Returning from this, the ship was to operate on the Southampton - Cherbourg - New York route, along with the Mauretania and Berengaria. During annual winter refits in 1926, 1927 and 1928 the passenger accommodation was extensively modernized.

In 1932 the Aquitania was used as a cruise ship for the first time. She left New York on 3rd February and cruised around the Mediterranean. Further cruises on this route and New York Bermuda route were accomplished later in the year. In November the ship underwent considerable internal reconstruction. First class accommodation was reduced to 650, tourist class was enlarged but the passenger accommodation reduced to 600 and third class was altered to cater for 950 passengers. All public rooms were renovated and a theatre was added. For the rest of the period up until the Second World War she continued a mixture of Atlantic crossings and cruises.

Due to World War 2, Aquitania was again requisitioned as a troop transport on 21st November 1939. At first she was used to transport Canadian troops to Europe. During 1940 she underwent a refit in America and was defensively armed with six inch guns. From March onwards she was based in Sydney transporting Australian and New Zealand troops, also making two passages between Pearl Harbour and San Francisco. For the remainder of the war she was employed on the Atlantic, and after the war had ended in the repatriation on Canadian and American troops. Later she was also used to to carry the wives and children of Canadian servicemen over to Canada.

On 1st April 1948 Aquitania was released by the Ministry of Transport and returned to Cunard. It was then chartered by the Canadian Government to carry Canadian emigrants between Southampton and Halifax. This contract was renewed in 1949. By 1st December 1949 this role had been fulfilled and later that month Cunard announced that the Aquitania would be withdrawn from service. She had, in fact, survived her original retirement date by 9 years.

On 9th January 1950 Messrs Hampton & Sons Ltd were employed to auction the vessels furnishings and equipment. Later that month the ship was sold to the British Iron & Steel Corporation Ltd for £125,000. The ship then sailed from Southampton to Faslane, in Scotland where she was broken up, this the end of the last of the four funneled liners.