A Cadmean victory is a reference to a victory

Victory

Victory is successful conclusion of a fight or competition..Victory may refer to:**strategic victory**tactical victory** Pyrrhic victory, a victory at heavy cost to the victorious party**Victory columns**Victory Monuments**Victory personified...

 involving one's own ruin, from Cadmus

Cadmus

Cadmus or Kadmos , in Greek mythology was a Phoenician prince, the son of king Agenor and queen Telephassa of Tyre and the brother of Phoenix, Cilix and Europa. He was originally sent by his royal parents to seek out and escort his sister Europa back to Tyre after she was abducted from the shores...

 (Greek: Kadmos), the legendary founder of Thebes

Ancient Thebes (Boeotia)

See Thebes, Greece for the modern city built on the ancient ruins.Ancient Thebes was a Boeotian city-state , situated to the north of the Cithaeron range, which divides Boeotia from Attica, and on the southern edge of the Boeotian plain...

 in Boeotia

Boeotia

Boeotia, also spelled Beotia and Bœotia , is one of the regional units of Greece. It is part of the region of Central Greece. It was also a region of ancient Greece. Its capital is Livadeia, the second largest city being Thebes.-Geography:...

 and the mythic bringer of the alphabet

Alphabet

An alphabet is a standard set of letters—basic written symbols or graphemes—each of which represents a phoneme in a spoken language, either as it exists now or as it was in the past. There are other systems, such as logographies, in which each character represents a word, morpheme, or semantic...

 to Greece

Greece

Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

. On seeking to establish the city, Cadmus required water from a spring guarded by a monster snake

Snake

Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

. He sent his companions to slay the snake, but they all perished. Although Cadmus eventually proved victorious, the victory was at the cost of lives of those who were to benefit from the new settlement.

Sources

• 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.
• Morford, Mark P. O. & Lenardon, Robert J., Classical Mythology, 7th ed. New York: Oxford University Press, 2002.
• Howatson, M.C. (Ed.) The Oxford Companion to Classical Literature, 2nd ed. New York: Oxford University Press, 2006.