Mainstream Leadership
Although though we often connect druids with secrecy and dark rituals, they spent decades as leaders for the Celts on both sides of the English Channel, not only priests, tribal chiefs, or anything so basic. They possessed judges, all offices relating to law enforcement, and administrative jobs such as astronomers for farming.
According to a druid's specific responsibilities, there were different colored robes, such as white for priests and blue for artisans. The Romans, who had effectively divided religion and the legal system by 451 BC, decades before their legions stepped foot in druid land, were particularly offended by the idea of priests executing the law.
Because Rome's emperors had it out for them specifically, Druids were forced to live underground. When Augustus Caesar's reign began in 27 BC, it appears that prohibiting Roman citizens from participating in their rites was one of his primary concerns.
A law prohibiting their execution was passed by the senate at the request of Emperor Tiberius. The Druids were completely outlawed by Emperor Claudius in 54 AD, ultimately forcing them out of all positions of authority. It must be acknowledged that the emperors had a point given that parts of those ceremonies will be incorporated in what we'll witness.