Conversation so far:
Where did Mirza go to school?
Mirza grew up and completed his schooling in Bombay, attending the Elphinstone College of the University of Bombay.
what did he study there?
but left the university to attend the Royal Military Academy in Sandhurst when he was selected by the British Governor.
in what year did he start his military service?
1920.

Question: where did he serve?
Self-contained rewrite: Where did Iskander Mirza serve his military service?