This is interesting as well
http://www.theguardian.com/world/2014/aug/02/muslim-soldiers-first-world-war
Extract:-
As many as 400,000 Muslims made up one-third of the Indian Army of 1.3 million, along with 100,000 Sikhs, and up to 800,000 Hindu soldiers. Yet when asked to estimate how many Muslims fought on the British side in 1914, only 2% of those surveyed by British Future correctly placed the number at between 250,000 and 500,000.