In the year 480 BC, King Leonidas led a force of Spartans in the defense of a mountain pass at Thermopylae, against an invading Persian army. The combatants battled heroically for two days, until the Spartans were defeated, having fought to their deaths against the Persians. This proved a pyrrhic victory for the Persians as the various Greek city states were able to use the time the Spartans made possible to rally their own defenses and defeat the invaders.
When Ezri discovered the battle had a theme ("Fighting to the last man!") similar to the Battle of the Alamo, and they were going to be the Spartans, she asked, "Have you ever talked to a counselor about these annihilation fantasies?" (DS9: "What You Leave Behind")