Belenus is the God of light and protector of sheep & cattle. His festival (Beltane) is May 1st. Traditionally cattle were led between 2 bonfires to gain his blessing, and people danced around a birch tree decorating it with ribbons. But the Romans outlawed that in the 4th century. The tree was replaced by a maypole - Christians haven't managed to ban that. Today it is also a holiday for the labor movement.
