Who is Captain Smith from If I Die in a Combat Zone, Box Me Up and Ship Me Home and what is their importance?

A short, fat, ROTC officer from Tennessee, Captain Smith, who is an ROTC officer from Tennesse, takes command when Captain Johansen finishes his tour and leaves Vietnam. Captain Smith is described as short, fat, careless, and not very skilled or brave in battle. He does not measure up to his predecessor.