Complex sentence: He can be just as pompous and officious as his chief rival, Mainwaring, but is by nature a more uncouth and coarse man, who delights in antagonizing the Home Guard platoon, in particular Mainwaring, who he always calls "Napoleon".
Split into simpler sentences: He can be just as pompous and officious as his chief rival, Mainwaring. Hodges is by nature an uncouth man, who delights in antagonizing the Home Guard platoon, in particular Mainwaring, who he always calls "Napoleon".