A Cadmean victory (Greek: Kadmeia nike) is a reference to a victory involving one's own ruin, from Cadmus (Greek: Kadmos), the legendary founder of Thebes in Boeotia and the mythic bringer of script to Greece. On seeking to establish the city, Cadmus required water from a spring guarded by a water-dragon similar to the Lernaean Hydra. He sent his companions to slay the dragon, but they all perished. Although Cadmus eventually proved victorious, the victory cost the lives of those who were to benefit from the new settlement.
The phrase "Cadmean victory" has been largely displaced in popular use by "Pyrrhic victory", which carries a similar connotation. However, there are also cases that battlefield Cadmean victories may be decisive in war, especially during the mid-19th up to the 20th centuries; such victory was achieved at the Battle of Stalingrad in World War II in which the winning side (the Soviets) lost so many men during the battle that only 10,000 men survived after the battle for the city, albeit achieving a decisive victory over the Nazis.
- Liddell, Henry George (Compiler), Scott, Robert (Compiler), Jones, Henry Stuart (Editor), McKenzie, Roderick. A Greek-English Lexicon, 9th ed. New York: Oxford University Press, 1995.
- Howatson, M. C. (Ed.) The Oxford Companion to Classical Literature, 2nd ed. New York: Oxford University Press, 2006. p. 105.
- Morford, Mark P. O. & Lenardon, Robert J., Classical Mythology, 7th ed. New York: Oxford University Press, 2002. p. 4.