Other stories suggest that Valentine may have been killed for attempting to help Christians escape harsh Roman prisons, where they were often beaten and tortured. According to one legend, an imprisoned Valentine actually sent the first "valentine" greeting himself after he fell in love with a young girl--possibly his jailor's daughter--who visited him during his confinement. Before his death, it is alleged that he wrote her a letter signed "From your Valentine," an expression that is still in use today.
While some believe that Valentine's Day is celebrated in the middle of February to commemorate the anniversary of Valentine's death or burial--which probably occurred around A.D. 270--others claim that the Christian church may have decided to place St. Valentine's feast day in the middle of February in an effort to "Christianize" the pagan celebration of Lupercalia. Celebrated at the ides of February, or February 15, Lupercalia was a fertility festival dedicated to Faunus, the Roman god of agriculture, as well as to the Roman founders Romulus and Remus.
To begin the festival, members of the Luperci, an order of Roman priests, would gather at a sacred cave where the infants Romulus and Remus, the founders of Rome, were believed to have been cared for by a she-wolf or lupa. The priests would sacrifice a goat, for fertility, and a dog, for purification. They would then strip the goat's hide into strips, dip them into the sacrificial blood and take to the streets, gently slapping both women and crop fields with the goat hide. Far from being fearful, Roman women welcomed the touch of the hides because it was believed to make them more fertile in the coming year. Later in the day, according to legend, all the young women in the city would place their names in a big urn. The city's bachelors would each choose a name and become paired for the year with his chosen woman. These matches often ended in marriage.
Lupercalia survived the initial rise of Christianity and but was outlawed—as it was deemed “un-Christian”--at the end of the 5th century, when Pope Gelasius declared February 14 St. Valentine's Day. It was not until much later, however, that the day became definitively associated with love. During the Middle Ages, it was commonly believed in France and England that February 14 was the beginning of birds' mating season, which added to the idea that the middle of Valentine's Day should be a day for romance.
Valentine greetings were popular as far back as the Middle Ages, though written Valentine's didn't begin to appear until after 1400. The oldest known valentine still in existence today was a poem written in 1415 by Charles, Duke of Orleans, to his wife while he was imprisoned in the Tower of London following his capture at the Battle of Agincourt. (The greeting is now part of the manuscript collection of the British Library in London, England.) Several years later, it is believed that King Henry V hired a writer named John Lydgate to compose a valentine note to Catherine of Valois.