As early as the 19th century, the weakened Ottoman Empire, from which Turkey would later emerge, was satirized as "The Sick Man of the Bosporus" by many media of the time. In the spring of 1915, the military and political situation was in many ways quite delicate for the Young Turk government. The Ottoman campaigns in the Russian-dominated Caucasus and northern Iran had failed and, as a result, the long front in the east had broken down in several places, and in the Ottoman province of Van, rebellious Armenian citizen militias were rising up against the encroachments of the province's military governor. In February 1915, the disarmament of the Armenian soldiers of the Ottoman armies began, some of whom were subsequently killed, others grouped into labor battalions. This was followed a little later by the execution, as it were, of the members of several of these battalions. Contrary to what is often portrayed, however, the Young Turks had by no means lapsed into passivity in the spring of 1915, but were intent on seizing what they saw as a propitious hour. After the Ottoman Empire had lost almost all of its territories in the Balkans in the wars of 1912/13, it sought large territorial gains in the Balkans during the First World War.
The neglected and disorganized state of the Ottoman army and navy after the Balkan wars resulted in the appointment of a German military mission with far-reaching powers under Liman von Sanders in 1913, which on the other hand caused increased vigilance and readiness for intervention by the Triple Entente. Although the Ottoman Empire maintained its neutrality until mid-summer 1914, it became more and more closely tied to the Central Powers. At the beginning of the war, on August 1, 1914, Great Britain had confiscated two Ottoman battleships commissioned and already paid for by the Ottoman Empire in England - the Reshadije and the Sultan Osman I, which was technically obsolete from the Royal Navy's point of view even before she was commissioned. The confiscation, ordered by Winston Churchill, caused general indignation in the Ottoman Empire, partly because the ships had been paid for with public donations. On August 2, Grand Vizier Said Halim and War Minister Enver had concluded a secret treaty with the German Empire, and on August 10, the German battle cruiser SMS Goeben and the small cruiser SMS Breslau under Rear Admiral Wilhelm Souchon had arrived in the Dardanelles after a sharp pursuit by the British Royal Navy. On 12 August they were nominally surrendered to the Sultan and renamed Yavuz Sultan Selim and Midilli; three days later the Ottoman government terminated the British naval mission under Admiral Limpus and expelled all British officers on 15 September. With German help, the Dardanelles were now to be fortified and the Bosporus secured against Russia by the Yavuz Sultan Selim. On September 27, 1914, the straits were officially closed to international shipping. With the Imperial German Navy blockading the Baltic Sea, Russia's sea links with the Western Allies were largely severed. The Bosporus and Dardanelles straits - the only route to the Black Sea - were now effectively controlled by the Ottoman Empire, making it almost impossible for the Western Allies to deliver weapons by sea.
On 29 October 1914, the Ottoman-flagged fleet under Admiral Souchon attacked Russian port cities in the Black Sea. Almost simultaneously, the Royal Navy fired on Ottoman merchant ships leaving the port of Izmir. As a result, on November 12, 1914, the Ottoman government declared war on the Triple Entente.
Towards the end of 1914, the fronts in Belgium and France had stiffened. The adversaries therefore considered seeking a decision elsewhere. The Triple Entente hoped that a direct attack on the Ottoman Empire might persuade the Greeks and Bulgarians to enter the war on the side of the Allies. Some contemporaries even believed that the Ottoman Empire would leave the war as an ally of the Central Powers if it won.
In April 1854, French and British troops had already landed at Gallipoli as part of the Crimean War. At that time, this happened under the opposite pretext, in order to prevent a possible Russian advance to Constantinople and with the express consent of the Ottoman Empire, with which a war aid treaty had previously been concluded on 12 March 1854. A little later the joint declaration of war against Russia was made. Both countries sent their Mediterranean fleets into the entrance to the Dardanelles and later into the Black Sea in June 1853.
An attack proposed by a French minister in November 1914 did not yet find sufficient support. A little later, the First Lord of the Admiralty, Winston Churchill, presented his plans for a naval attack on the Dardanelles. On 16 February 1915, the British decided for the first time to launch a major landing operation. War Minister Lord Kitchener appointed General Sir Ian Hamilton as Commander-in-Chief of the Expeditionary Force, which was to carry out the operation.
After entering the war, the Ottoman defences of the Straits were considerably strengthened. The number of underwater mines was more than doubled, additional guns and batteries were emplaced, and stronger fortifications were erected. Churchill was able to persuade the Allies to launch a major assault on the Dardanelles after weeks of negotiations, and as a result is generally regarded as the main man responsible for the operation. The large-scale frontal assault against the fortified Ottoman positions on the Gallipoli Peninsula required the massing of numerous warships. Churchill believed that the guns of the British battleships would outrange the enemy guns and thus destroy the forts and fortifications without danger. This, as was later shown, was a misjudgement. However, he was so convinced of a pure naval attack that he still wanted to continue it at the end of February, when he himself already realized that additional land forces were urgently needed for the conquest of the peninsula.