Winston Churchill was the earliest proponent of the Gallipoli Campaign. The Dardanelle Straights had great strategic value because they connected the Mediterranean Sea with the Sea of Marmora, and provided access to the Turkish Capital and the Black Sea. This route would allow the Allied Forces to supply Russia, but also force Bulgaria and Greece to choose sides in the war. However, the terrain of the Gallipoli peninsula made the straits easy to defend against invasion and several fortresses had been built in positions close to shipping lanes.
Turkey had initially been neutral in the war. However, a debacle involving two battleships being built for them in British shipyards alienated them from Allied Forces and ultimately resulted in their entry into World War I on the side of the Germans. At that time, the campaign on the Western Front was deadlocked in trench warfare and the British and French governments decided to establish another front in the Mediterranean in hopes of improving the tactical situation.
Winston Churchill pitched a detailed plan to the British War Cabinet in the early months of 1915. While some were in favor of his idea, some naval commanders were not in favor of Churchill's approach. Nevertheless, Churchill's plans for an attack were eventually approved by the cabinet despite opposition from the navy to reallocating several older ships from their mission in the North Sea where actual threats existed.
The initial attacks of February 1915 ended quickly in failure. The straights were heavily protected by underwater mines and Turkish mobile artillery was very effective at delivering indirect fire at the fleet of battleships. It quickly became clear that ground support would be required to take control of the straights. Allied forces took a month to organize and train their invading forces. During that time the Turkish prepared for the attack by building obstacles and emplacing land mines. German...