Trench warfare
Trench warfare occurred when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire, mines, camouflaged trapping pits, and other obstacles. The area between opposing trench lines (known as "no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
Gallipoli Campaign
By late 1914 the war on the Western Front had become a stalemate; the Franco-British counter-offensive of the First Battle of the Marne had ended and the British had suffered many casualties in the First Battle of Ypres in Flanders. The war of manoeuvre ended and trench warfare began. The German Empire and Austria-Hungary closed the overland trade routes between Britain and France in the west and Russia in the east. The White Sea in the arctic north and the Sea of Okhotsk in the Far East were icebound in winter and distant from the Eastern Front, the Baltic Sea was blockaded by the "Kaiserliche Marine" (Imperial German Navy) and the entrance to the Black Sea through the Dardanelles was controlled by the Ottoman Empire. While the empire remained neutral supplies could still be sent to Russia through the Dardanelles but prior to the Ottoman entry into the war the straits had been closed and in November the Turks began to mine the waterway.