Basra. During this period, she escorted an Indian troop convoy to Bahrain in mid-October; the convoy had departed India on 16 October, and Ocean met the convoy at sea three days later to take over escort duties. After the convoy arrived on 3 November, Ocean began making preparations for the attack on Basra. Numerous small craft were armed to enter the Shatt al-Arab, the river leading to Basra. The first objective was to silence the old fortress at Al-Faw. On 5 November, Britain declared war on the Ottoman Empire, and the next morning, Ocean began the bombardment of Al-Faw. A landing party of 600 men, some of whom came from Oceans detachment of Royal Marines, stormed the fortress and captured it, having encountered no resistance. By December 1914, the ground forces Ocean supported had advanced to Al-Qurnah, at the juncture of the Euphrates and Tigris, allowing the Admiralty to recall Ocean for other purposes. She was accordingly stationed at Suez, Egypt, to assist in the defence of the Suez Canal, arriving there on 29 December. She anchored in the mouth of the southern end of the canal on 29 December and remained in that area until mid-January 1915, when she proceeded northward up the canal. On 3–4 February, she and the armed merchant cruiser Himalaya supported ground troops against an Ottoman attack on the canal in the vicinity of El Kubri. Later on the 3rd, after the Ottoman attack at El Kubri had been defeated, Ocean was sent to Deversoir to provide artillery support to the garrison there, but Ottoman attacks were insignificant. By the following day, the Ottoman assault had broken down completely. Dardanelles campaign and loss Ocean transferred to the Dardanelles in late February 1915 to participate in the Dardanelles campaign. On 28 February, she took part in an attempt to suppress the Ottoman defences in the Dardanelles led by Admiral John de Robeck; the battleships Albion and led the operation, and were tasked with neutralizing the repaired fortress at Dardanus, while Ocean and supported them by engaging batteries of mobile field guns that had proved to be troublesome in previous attempts to neutralise the Ottoman defences. Ocean initially attempted to locate guns that had been active in the vicinity of Sedd el Bahr, before moving on with Majestic and coming under fire from several Ottoman batteries, including howitzers around Erenköy. The British battleships eventually silenced the guns,