The man is often a member of the military stationed overseas, although the letter may be used in other ways, including being left for him to discover when he returns from work to an emptied house.
"John" was the most popular and common baby name for boys in the United States every year from 1880 through 1923,[1] making it a reasonable placeholder name when denoting those of age for military service.
Large numbers of American troops were stationed overseas for many months or years, and as time passed many of their wives or girlfriends decided to begin relationships with new men, rather than wait for the soldiers to return.
One of the earliest notable Dear John letters was written by Agnes von Kurowsky to Ernest Hemingway in 1919.
[2] As letters to servicemen from wives or girlfriends back home would typically contain an affectionate greeting (such as "Dear Johnny", "My dearest John", or simply "Darling"), a serviceman receiving a note beginning with a curt "Dear John" when accustomed to a warmer greeting would instantly be aware of the letter's purpose.