Brigante Queen Cartimandua of Roman Britain
Cartimandua probably gets a less kind press then she deserves. I think the reason for this is because she does not have the Boadicea glow of the famous Celtic warrior queen. Writers of romantic historical fiction and followers of Celtic myth often present her in less kind ways. On the other hand, she lived in harsh times and perhaps, made tough decisions for the greater good.
Because Celtic society enabled woman to hold more powers then most; Celtic ladies are often made Icons. Much of this is due to legend and fascinations - plus, of course, Queen Boadicea of the Iceni Britons. Not all were as bold as Queen Boadicea, but perhaps some were more successful then given credit for. It is difficult to say if Queen Cartimandua was a traitor or someone trying to make the best of a bad situation.
If this was so, why did Caratacus take the chance of standing before Cartimandua and asking for sanctuary? He had been fighting the Romans for a number of years and would surely know that she was allied to the them. Maybe he was trying to reach Caledonia (Today's Scotland) and was captured passing through - who knows?
This act of betraying Caratacus caused a rift among the Briganties and Cartimandua's husband Venutius became opposed to her. He tried to usurp her power and take the Brigante kingdom for himself. This was in 50 AD.
She was able to count on the friendship of a man called Vellocatus who was once a subordinate of her husband Venutius. Also the Romans sent her aid with an army. With the help of Rome and her loyal followers she was able to defeat and drive Venutius away.
The Roman historian Tacitus mentions her as a friend of Rome and for a further 19 years she would remain in control and collaborating with Rome. When the Iceni Queen Boadicea (Boudicca) led her rebellion, Cartimandua would not send Brigante forces to aid the Iceni queen. It is possible that such requests never came to her.
Cartimandua's exiled husband Venutius remained in his sanctuary watching and waiting. Then in 69 AD - some nineteen years after being driven out of the Brigante lands, Rome was weakened by its own internal political strife. It was the year of four Emperors. Venutius launched an invasion of the Brigante lands and Cartimandua could only get limited help from the Roman administration. She was driven out of Brigante and into the sanctuary of Roman held territory. She never returned and history lost account of what became of her.
It is not known exactly when or if Venutius was brought to account for his anti Roman invasion or if he remained their chieftain/king, but the Brigantes would remain un-pacified as a people for several decades to come until the early part of the second century.
Cartimandua faded from history and no one knows when she died. She never reclaimed her kingdom and many Celts believed her to be treacherous. Maybe the Romans thought so too. Perhaps she was no longer of use to them once she fled the Brigante lands. With no confidence in her continued ability to keep the Brigantes in check, she was persuaded to retire into another region of the Empire and live in anonymity.