The vast scale of the Great War and the heavy casualties sustained meant that officers needed to be found badly to fill vacancies in established and newly raised units.
One very important source for this was the Indian Army Reserve of Officers (IARO). Many men in the IARO lived and worked in India and often had some military background.
Although not career soldiers, Indian Army Reserve Officers often received high praise from the units that received them, and did much valuable work in which ever theatre they found themselves.
Commonwealth War Graves
Death and Service 