There are several ways to start your letter! But make sure it is correct for the branch you intend to address! 
Across all branches:
“Dear American Hero,”
“Dear Service Member,”
“Our United State Military,”
ARMY:
“Dear Soldier,”
NAVY:
“Dear Sailor,”
AIR FORCE:
“Dear Airman,”
MARINE CORPS:
“Dear Marine,”
COAST GUARD:
“Dear Coast Guard,”
It is common to write letters to “Dear American Soldier”, but remember…that is only how you address someone in the ARMY. Let’s include all branches!
