The first attempt to launch the ship failed on 23 March 1909 as the tallow used to lubricate the slipway had frozen and Otranto ground to a halt after sliding only 20 feet (6.1 m).

Attempts to persuade her to resume her progress with hydraulic jacks failed and the slipway had to be partially rebuilt before she was successfully launched four days later.

Otranto arrived from London, via ports, early yesterday morning, and, after being granted pratique, made fast to the quay a little before 9 o'clock Captain Coad reported an uneventful voyage.

The Otranto is the first of the new Orient liners to be fitted with wireless, and during her present trip she was able to maintain communication with 23 shore stations and 45 steamers.

Western Australia's proportion consists of 164 bags, whilst the balance is distributed as follows:— Adelaide, 125; Melbourne, 272; Geelong, 8; Ballarat, 18; Bendigo, 10; New South Wales, 346; Queensland, 169; Tasmania, 45; New Zealand, 495; H.M. fleet, 18; Noumea, 30.

She was present at King George V's Coronation Naval Review on 26 June and made several voyages to the Norwegian fjords before mid-September when she returned to the Australia run, on which she remained until war was declared on Germany on 4 August 1914.

[6] The Admiralty requisitioned Otranto on that same day for conversion to an armed merchant cruiser, having eight quick-firing (QF)4.7 in (120 mm) guns fitted.

Half-inch (12.7 mm) steel plating was added to protect her steering gear and her interior cabin bulkheads and glass ventilators were removed to reduce damage from splinters.

The ship departed the UK on 17 August, the second armed merchant cruiser to leave England, with sealed orders that assigned her to Rear Admiral Sir Christopher Cradock's West Indies Squadron in the South Atlantic.

[8] Otranto accompanied Cradock and three cruisers to patrol the Strait of Magellan and the Chilean coast for German ships in mid-September.

[9] In mid-October Otranto struck a rock while departing Port Legunas, Chile, but a diver from Monmouth reported that it had done very little damage.

[10] On 27 October Cradock ordered Otranto to investigate Puerto Montt for signs of German ships and sent Glasgow to Coronel, Chile, to pick up any information from the Admiralty.

[11] At this time, both sides thought that they were in pursuit of a single light cruiser as a German merchantman had reported Glasgow's presence in Coronel to von Spee earlier in the day.

There she remained until 4 February 1915 when she returned to the UK where she arrived at Birkenhead on 10 March[16] to begin a refit where her 4.7-inch guns were replaced an equal number of 6-inch (152 mm) weapons.

[19] Otranto arrived at Rio de Janeiro, Brazil, on 30 April and helped to salvage the cargo liner Highland Scot that had run aground on Ilhas das Maricás in the harbour on 6 May.

Six days later, on the evening of 1 October, the ship accidentally rammed the French fishing schooner Croisine off Newfoundland while the latter was returning home to St. Malo with a full load of cod.

Both ships attempted to avoid the collision, but their efforts cancelled out and Kashmir rammed Otranto on the port side amidships, a few miles off the rocky coast of Islay.

When the engine room flooded shortly afterwards, Otranto lost all electrical power and began to drift towards the cliffs of Islay.

The water pressure caused other bulkheads to collapse, quickly flooding other spaces below the waterline and giving the ship a massive list to starboard.

By the following morning, the liner had been completely demolished by the heavy seas and the coastline was strewn with wreckage and hundreds of bodies in piles up to 15 feet (4.6 m) deep.

[25] The police sergeant at Bowmore, Malcolm McNeill, the maternal grandfather of a later (1999-2004) NATO general secretary, George Robertson, commended local people in his report: 'though they had so little, they gave so much to help' and also responded to enquiries from the American families of those lost from the Otranto (and in the 1918 SS Tuscania sinking).

[26] Craven was awarded the Distinguished Service Order and the Navy Cross for gallantry displayed in Mounsey's rescue operation.

And an 80-foot (24.4 m) stone tower was built on the Mull of Oa by the American Red Cross to commemorate the men lost aboard Otranto and Tuscania which was sunk by a German U-boat nearby.