It is perfectly obvious that the script writer for this film never got closer to the sands of Iwo Jima than Laguna Beach. He has, however, read several lousy war books, from which he has gleaned that 1.) all sergeants are tough, but underneath they are just like anyone else; 2.) the boys on the beachheads are more preoccupied with life around the corner drugstore back home than they are with the war immediately at hand; and 3.) the Marines have a great tradition.
The producers take care of point one by casting steel-eyed John Wayne in the role of tough Sergeant. It is only a matter of minutes before you are led to realize that this man is a True Marine, who has seen action on Guadalcanal (referred to with reverence as "The 'Canal"). It is also explained clearly that his wife has deserted him in some dastardly fashion, taking his ten-year-old son, his pride and joy. (That's why he's tough, see). But it isn't until halfway between the Tarawa and Iwo campaigns that he shows his true nobility by feeding Pablum to the infant son of a girl he has picked up in a bar instead of carrying the interview to its logical conclusion.
Innumerable insights into the heart and mind of the American Fighting Man are provided in the several battle scenes. One by one the maudlin leather necks in Sergeant Wayne's squad soliloquize eloquently on the girls they left behind them, what they are going to do when they get back home, or even Why America Must Fight This Terrible War. Such elocution is invariably the signal for the speaker to be picked off.
As if Wayne's home life weren't enough, one of his men is an earnest youth who hates the Corps but feels he must carry on the tradition of his Colonel father, killed on The 'Canal. The young man's lack of adjustment causes all sorts of bad feeling, but is resolved in very moving fashion. Sergeant Wayne gets his just as Old Glory goes up over Mount Surabachi, and his squad takes a breather to read an unfinished letter he has been writing his little boy. The young man is so moved by this epistle that he forgets his neurosis and takes over the remnants of the squad, leading them off into the smoke of battle once more.
You also see shots of the famous flag-raising. Very statuesque, if I do say so.