Queen Boudica was the ruler of the Iceni tribe back during the Roman occupation of Britannia. When her husband, Prasutagus died, she and her daughters were to assume join control of his kingdom as stated in his will. The Romans wouldn't stand for that however, and so they beat Queen Boudica and raped her daughters. Naturally pissed off by this, she gathered various tribes together and led them to Londinium (Which is London today), killing everyone in her path. When she and her forces arrived at Londinium, they slaughtered everybody there and then burnt the city to the ground.
If you'd like to know more, here's the Queen Boudica Wikipedia page!