Complex sentence: Tanaka was attached to the 1st Heavy Field Artillery Regiment from 1934 to 1935, then attached to the 2nd Section of the Kwantung Army staff from 1935 to 1937.
Split into simpler sentences: Tanaka was attached to the 1st Heavy Field Artillery Regiment from 1934 to 1935. Then attached to 2nd Section of the Kwantung Army staff from 1935 to 1937.