The Spanish Civil War was an armed conflict that erupted after a conservative-backed military coup to depose Spain’s republican government failed to gain control over the whole country. A bloody three-year war ensued with the Nationalists supported by fascist states like Italy and Germany, and Republicans supported by the Soviet Union and the Left across Europe and the US. Around 40,000 volunteers fought in Spain as part of the International Brigades, which were largely controlled by the Comintern, among them George Orwell and Mulk Raj Anand. The Spanish Civil War ended with the disbanding and surrender of Republican armies at the end of March 1939. The conflict cost an estimated 500,000 - 1,000,000 lives. For Britain it marked a threat to the post-World War I international consensus which would lead to the outbreak of the Second World War.

The conflict’s political impact reverberated far beyond Spain. It was seen as an international conflict and part of a wider struggle between freedom and democracy versus tyranny, dictatorship and fascism. It became a conflict of different conceptualizations of civil society and a struggle for people’s rights to self-determination, democracy and world peace. In the context of India’s struggle for independence it became evident that its own fight for self-determination was linked to other international conflicts like the Spanish Civil War. Nehru and Krishna Menon in particular realized this.

The conflict mobilized many Indian citizens living in Britain. For example Indira Nehru spoke in support of Republican Spain at a gathering organized by Krishna Menon. The January 1938 India League independence day demonstration also highlighted the conflicts in China, Abyssinia and Spain. Along with banners of Nehru and Gandhi, flags of Republican Spain were visible. The India League in collaboration with the Communist Party of Great Britain and other organizations on the Left held meeting and protest marches in support of Republican Spain. Menon and Nehru visited Spain in summer 1938 and Nehru addressed a crowd of 5,000 in Trafalgar Square as part of a demonstration in Aid of Republican Spain on 17 July 1938, which marked the second anniversary of the start of hostilities. The India League also founded the Indian Committee for Food For Spain, with Feroze Gandhi as organizing secretary. Menon and Clemens Palme Dutt combined forces and engaged in fund-raising activities for an ambulance.

As in the First World War, Indian soldiers were called upon by Britain to help in the war effort. Despite the constitutional fall-out from Britain’s declaration of war on behalf of India, without prior consultation of Indian representatives, Britain could nevertheless rely on India’s support. The massive involvement of men and women from India in Britain's war effort and her allies has remained a marginalized story of the Second World War. Indian soldiers provided manpower, equipment and auxiliary support in theatres of war throughout the world. Their contribution was vital to keep the supply lines to Britain open and to defend her borders at home and in the empire.

An Indian contingent provided vital backup to the British Expeditionary Force in France in 1940 and these mule transport companies were evacuated at Dunkirk and received praise from British officers for their discipline and exemplary conduct in the midst of chaos. They were stationed in Britain until 1943 to provide vital back-up on the home front. South Asians in Britain such as Cedric Dover and Sudhindra Nath Ghose worked as ARP Wardens in Civil Defence. Indian pilots such as Mahinder Singh Pujji, one of seven fighter pilots chosen to join the RAF, flew Hurricanes, engaging German aircraft in dogfights over the English Channel. He was one of 24 Indian Air Force pilots sent to Britain in September 1940 to fly with the RAF (including four other Sikh pilots: Shivdev Singh, Gurbachan Singh, Tirlochan Singh and Manmohan Singh). Tirlochan Singh and Air Marshal Shivdev Singh flew bombers, the latter making twenty-two operational flights over Germany and later commanding an Indian Air Force squadron in Burma. The Royal Air Force needed to make up a shortage in pilots by actively recruiting personnel from across the Commonwealth. It dispensed with the colour bar of the armed forces that stipulated that only ‘British subjects of pure European descent’ could join. After October 1939 people from across the Commonwealth, regardless of nationality or race became eligible to join the RAF. By the end of the Second World War, over 17,500 such men and women had been recruited, serving in a variety of roles. A further 25,000 served in the Royal Indian Air Force.

In addition to meeting her own requirements, India’s new factories maintained a regular supply of vital war materials to her Allies. Textiles were sent to 15 countries. India would supply 37,000 of the 50,000 different textile articles required by the United Nations in the war. India was the third largest consignor of supplies to Australia for the Pacific war. Russia and China also received much war material from India.

South Asian merchant seamen living around the ports of London, Cardiff, Liverpool and South Shields also played a significant role. These sailors helped to ensure that the supply lines to Britain remained open and provided vital manpower often working under atrocious conditions for less pay than their white counterparts.

The Indian Army played a major part in the operations in Italy, the Mediterranean, the Middle East, East Africa and the Far East. The Fourteenth Army in Burma was the largest single army in the world. Its battle front of 700 miles was approximately as long as the Russian front against Germany. Of the total force of 1,000,000 men employed in Burma ( S.E.A.C.), 700,000 were Indians. By the end of the war, the Indian Army won 31 Victoria Crosses. In all, 4,028 awards for gallantry were made. In WWII the Indian Army suffered 24,338 killed, 64,354 wounded and 11,754 missing.