Who is Lieutenant Mac from With the Old Breed, at Peleliu and Okinawa and what is their importance?

Lieutenant Mac is the nickname given to the mortar section commander, a commissioned officer, arriving between Peleliu and Okinawa. Sledge offers little biographical data on Mac, probably to obscure his identity as he is portrayed in an unfavorable light. He is a New Englander and an Ivy League graduate; blonde and of average size. Mac is well-built, energetic, and talkative. He performs his duties in a conscientious method but is a braggart and has little common sense. After taking command of the veteran unit, the inexperienced Mac brags about how he will charge the Japanese with a knife in his teeth and a pistol in his hand to repay them for the first marine casualty. Such braggadocio does not impress combat veterans; Mac's continued bragging rubs all of the men the wrong way and he is not well liked.