By early 1915, the war on the Western Front had reached a
stalemate. While lines of trenches stretched through Flanders and
France, Russia was struggling to resist the forces of Germany and
Austria-Hungary in the east. In response to a request for aid from
its ally, the British War Council sanctioned a plan to attack the
Ottoman Empire, which was fighting alongside the Central Powers
against both Russia on its northern frontiers and against
British-led forces in the Middle East.
By sending Allied warships through the narrow straits of the Dardanelles
to attack Constantinople (now Istanbul), it was hoped that the
Ottomans could be forced out of the war.