Although the trigger for the First World War was seen as the assassination of Archduke Franz Ferdinand in Sarajevo on 28 June 1914, Britain declared war on Germany in August 1914. As Britain and France waged war against Germany in Europe and in Africa, Britain called upon help from her Imperial troops. Indian soldiers in the Indian Army arrived in Europe from September 1914. The first of these Indian troops arrived in Marseilles on 26 September 1914. They came from the Lahore and Meerut Divisions and the Secunderbad Cavalry. In October, Indians were fed into some of the fiercest fighting at Ypres. In March 1915, Indian troops provided half the attacking force at the Battle of Neuve Chapelle, which was the costliest in terms of lives.

By 1918, India had sent over 1 million soldiers to fight in the War, not including Imperial Service Troops from the Princely States, Sailors and Indian Labour Corps. 138, 608 Indian soldiers (two infantry divisions, two cavalry divisions and four field artillery brigades) saw action on the Western Front. Here, 7700 Indians died, 16,400 were wounded and 840 went missing or were taken prisoner. Of the twelve Victoria Crosses awarded to Indians after the War, six were for those who had fought on the Western Front. The main memorial to the Indian Army on the Western Front was that designed by Sir Herbert Baker, and opened in 1927 at Neuve Chapelle.

Wounded Indians who had fought in France were sent to Britain to recover. In Brighton, the Royal Pavilion was transformed into a military hospital for Indian soldiers. During their time spent recuperating, Indians were visited by the King and the Royal Family. Tours were also organized for them to visit London and see the sights. The religious needs of the soldiers was taken into account, with nine kitchens erected to cater for the various dietary regulations of Hindus, Sikhs and Muslims and areas were cordoned off for worship. Various other buildings were also converted into nursing homes for these soldiers. Two memorials exist in Brighton to commemorate the Indian soldiers who came through during the War - the Chattri on the South Downs and the Pavilion Gateway (unveiled by Bhupinder Singh in 1921).