He was the son of Euphorion from Eleusis and member of the Eupatridae, the ancient nobility of Attica. In 490 BC Cynegeirus and his brother Aeschylus fought to defend Athens against Darius's invading Persian army at the Battle of Marathon. Despite the numerical superiority of the Persians, they were routed and fled to their ships. The Athenians pursued the Persians back to their ships, and Cynegeirus in his attempt to push away a Persian ship with his bare hands had his hand cut off at the wrist and died. According to another version of his death, recorded by the Roman historian Justin, when Cynaegyrus lost his right hand, he grasped the enemy's vessel with his left. Here the hero, having successively lost both his hands, hangs on by his teeth, and even in his mutilated state fought desperately with the last mentioned weapons, " like a rabid wild beast!"
The incident of the heroic death of Cynegeirus became an emblem of cultural memory in ancient Greece and was described in literature in order to inspire patriotic feelings to future generations. It was also painted by Polygnotus on the Stoa Poikile in Athens in 460 BC, while the ancient traveler and geographer Pausanias described the painting in his 2nd century AD work.
- Bates, Alfred (1906), The Drama: Its History, Literature, and Influence on Civilization, Vol. 1, London: Historical Publishing Company
- van Dijkhuizen, Jan Frans (2004). Living in posterity: essays in honour of Bart Westerweel. Uitgeverij Verloren. p. 242. ISBN 978-90-6550-839-3.
- Dictionary of Greek and Roman Biography and Mythology by William Smith (1870).
- Maximus Valerius (2004). Memorable deeds and sayings: one thousand tales from ancient Rome. Hackett Publishing. p. 90. ISBN 978-0-87220-674-8.