Supposed to be an antidote against lightning, because it was the tree of Apollo. Hence Tiberius and some other of the Roman emperors wore a wreath of bay as an amulet, especially in thunder-storms. (Pliny.)
Reach the bays- I'll tie a garland here about his head; `Twill keep my boy from lightning.
The White Devil.
The withering of a bay-tree was supposed to be the omen of a death.
`Tis thought the king is dead. We'll not stay- The bay-trees in our country are withered.
Shakespeare: Richard II., ii. 4.
Crowned with bays in sign of victory. The general who obtained a victory among the Romans was crowned with a wreath of bay leaves.
Bay The reason why Apollo and all those under his protection are crowned with bay is a pretty fable. Daphne, daughter of the river-god Peneos, in Thessaly, was very beautiful and resolved to pass her life in perpetual virginity. Apollo fell in love with her, but she rejected his suit. On one occasion the god was so importunate that Daphne fled from him and sought the protection of her father, who changed her into the bay-tree. The gallant god declared henceforth he would wear bay leaves on his brow and lyre instead of the oak, and that all who sought his favour should follow his example.
The Queen's Bays. The 2nd Dragoon Guards; so called because they are mounted on bay horses. Now called The Queen's.
Bay. The colour of a horse is Varro's equus badius, given by Ainsworth as, “brown, bay, sorrel, chestnut colour.” Coles gives the same. Our bayard; bright bay, light bay, blood bay, etc.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894