Complex sentence: Joining in 1938 and being posted to the NW frontier Although promoted to acting, and then temporary captain from September 1940, (and substantive lieutenant on 3 January 1941) his time in India was mostly spent on exercises with little chance of action.
Split into simpler sentences: Joining in 1938 and being posted to the NW frontier He was promoted to acting, then temporary, captain from September 1940, and substantive lieutenant on 3 January 1941. His time in India, however, was mostly spent on exercises with little chance of action.