April 30th (eve.) through May 1st (day), May 5th if corrected to our modern calendar.
The Spring Crossquarter: Beltane, pronounced "BALCH in ah", approximately marked the halfway point between the Vernal Equinox and the Summer Solstice; the middle, or crown of Spring. Other names: May Day/May Eve; Walpurgis(nacht).
Much has been written of the apparent division of the Celtic year into two halves: a dark half from the great bonfire night of Samhain (All Hallows), through the winter and on to the fires of May Eve; and the bright half: from May Day on through the summer, along to Samhain again. The eves of these two thresholds of the year were said to be dreadful nights when the veil between this world and the Otherworld was thinnest, and consequently, over the centuries there has accumulated much lore of magical events and magical encounters transpiring on these nights.
As fearful of the Eve of May the people were, all the more eager they were for the revelry of the day to come... a descendant of the Roman feast of flowers, the Floralia: Maypole dancing, Morris Dancing, Mummers plays and May caroling are but a few of the persistent May Day traditions that the Puritans tried vainly to extinguish during the Reformation. These joyous celebrations of the Crown of Spring; the Threshold of Summer were too deeply entrenched in the lives and history of the people to be snuffed out by the Church's railing against their "heathen ways".
Floralia, the Roman feast of Flora, Goddess of the Flowers; Queen of Spring, may possibly be at the root of some of the popular British Mayday customs with which we are familiar. Still current in medieval times a thousand years later and cherished and protected by the common folk and gentry alike through the harshness of the Protestant Reformation right up to the current day-- the spirit behind these practices clearly reflects the European Ancestors' passionate love and reverence for Springtime and Her flowers.
Even today in America as well as in the Old Countries, children rise before the sun to gather and decorate baskets of May-morn' flowers and later, just as generations of their ancestors did, once more they'll dance 'round and 'round, braiding the gaily ribbon-bedecked Maypole, the ancient symbol of fertility and phallic potency (ironically, now more often at parochial schools!). Above them, sighing on the winds from across the sea and across the ages, you can almost hear the old maysong: "Summer is a cumin in!"