1915 began in a more sombre mood. The initial enthusiasm of the French had been tempered by massive losses. The Germans, although they had thoroughly beaten the Russians on the Eastern front, had been flung back at the battle of the Marne. The British Army was facing up up to modern warfare on a scale it had not prepared for. The War spread to Africa, the Middle East, and brought in Italy and Bulgaria on opposite sides.
The Germans began two new campaigns - with Zeppelin attacks from the air and unrestricted U-Boats attacks against merchant and passenger ships around the British Isles. including the sinking of the Lusitania.
The French Army launched another disastrous attack in the Champagne region. The second battle of Ypres saw the first use of poison gas against the British. Faced with the appalling conditions and casualties on the Western Front some British politicians (including Winston Churchill) and their military advisors began to look for other fronts where Britain’s naval forces could be involved.
In the Middle East the British began a long campaign against the Turkish armies in Mesopotamia with an initial success at the battle of Kut-al-Amara. Meanwhile in the West the British Army used a combination of poison gas and increased artillery support to punch a hole in the German lines at the battle of Loos which was not properly exploited. From this failure much was learned by the British High Command.