The Indian Army was reorganized by Lord Kitchener while he was commander-in-chief in India (1902-09). Kitchener established an army of 10 divisions (155,000) backed by an internal security force of some 80,000 troops. About a quarter of the infantry and cavalry troops and almost all artillery personnel in the army were British.

Two divisions and a cavalry brigade of the Indian Army was sent to the Western Front in September 1914. Of the 70,000 sent to France, 5,500 were killed and well over 16,000 wounded. As a result of a suggestion made by King George V, the Royal Pavilion in Brighton was converted into a hospital for wounded Indian soldiers. It has been claimed that several soldiers been brought in unconscious, woke up in the Banqueting Room, and thought they had died and were in Paradise.

As well as the Western Front the Indian Army was also sent to Mesopotamia, Gallipoli, Palestine, East Africa and Egypt.

By November 1918 the Indian Army contained 573,000 men and more than 1.3 million men served during wartime, of whom about 72,000 men were killed.