'The mighty chiefs sleep side by side;
Drop upon Fox's grave the tear,
'Twill trickle to his rival's bier.'
Walter Scott's first line above refers to the two William Pitt's; the Elder Lord Chatham, and the Younger, who died on January 23, 1806. Line two, the Whig Charles James Fox, rival of Pitt the Younger.
Pitt's public career included functioning as a prime minister from 1783 - 1801 and again between 1804 - 1806. This timeframe includes the great events of the era; the French Revolution and the Napoleonic Wars. Pitt's career was necessarily shaped by these events.
One outcome of these times, which Pitt actively supported, was the uniting of Ireland with Great Britain; the Act of Union of 1800. In one respect, a defensive measure, as Irish nationalists had attempted a rebellion in 1798, and the threat of intercession from France was considered great.
Pitt, in his second ministry encouraged Great Britain's involvement in the Third Coalition, joining Austria, Russia, and Sweden against Napoleon. Not long after, in October 1805, Horatio Nelson prevailed over the French at the Battle of Trafalgar, establishing English naval supremacy for the duration of the war.
Pitt figures prominently in Scott's "The Life of Napoleon".