Matthew Broderick Was Too Old for this Film!
I looked him up. Matthew Broderick was born in 1962 and this film was released in 1989. If they spent a year making it, he was 26 years old when they did most of the filming.
Robert Gould Shaw enlisted at the age of 23. If that was as early as April of 1861 when the war started (started by those rebels firing on Federal property at Fort Sumter, mind you), then he was only 25 years old in 1863 when he died (killed by the rebels again) at Fort (or Battery) Wagner.
Matthew Broderick was a year too old to be playing Colonel Shaw!
The best diplomat I know is a fully charged phaser bank.