Various legends are related to Valentines Day out of which one is that of Feast of Lupercalia and other is of martyrdom of Saint Valentine
. The linking Valentine's Day with love in Middle Ages was strengthened by the notion that birds began to look for mate during this time of festival. Valentines Day gained much popularity in the middle ages when lovers exchanged simple gifts like flowers, chocolates and cards.
In the middle ages it was believed in France and England that the birds mating season began from February 14th that is why middle of February is celebrated as a day of love. Further in fourteenth and fifteenth centuries English and French poets linked Valentines Day with their poems and verses.
Charles was a Duke of Orleans wrote the first card to his wife when he was imprisoned in the Tower of London in 1415. That Card is a part of manuscript collection of British Library in London. It is also said that saint valentine of Rome also sent a letter to the daughter of jailer when he was in jail and wrote From your Valentine at last. This phrase is still popular.
Legends that influence Valentines Day are:
First legend states that the festival originated from the feast of Lupercalia which is known to be a fertility festival celebrated in mid February.
Another legend state that a priest called St Valentine lived in Rome and was executed by Claudius on February and he became patron saint of lovers so this day is celebrate his martyrdom.