The story of the Persian messengers who demanded earth and water from the Spartans is well known. To the Persians, this request for earth and water was a sign of submission and obedience, a request the Spartans strongly refused. They were thrown into a well by the Spartans, and told that they would find both of each down there. However, the sequel to the story is lesser known.
The Spartans later regretted this incident so greatly, for it was undeniably an immoral act, that they sent two citizens to Persia, who volunteered to be killed by them in order to erase the Spartans’ guilt from their own crime.