'Mr Pitt, as a traitor of the nation'
William Pitt the Younger (1759–1806) was Britain's Prime Minister at this time. The second son of Pitt the Elder, who was Prime Minister from 1766–1768, the second Pitt was the youngest Prime Minister Britain has had to this day, rising to the position at the age of only twenty four. He held this position twice: once from 1783–1801 and then again from 1804 until his death in 1806, shortly after the Battle of Austerlitz.
Pitt the Younger governed Britain's recovery following the American War of Independence. He was an important supporter of the abolition of the slave trade, and a determined enemy of Napoleon. Pierre is, at this time, a fervent admirer of Napoleon, so Pitt is nothing more than a traitor in his eyes.