Andrew Roberts's magnificent new biography portrays George as intelligent, benevolent, scrupulously devoted to the constitution of his country and (as head of government as well as head of state) navigating the turbulence of eighteenth-century politics with a strong sense of honour and duty. He was a devoted husband and family man, a great patron of the arts and sciences, keen to advance Britain's agricultural capacity ('Farmer George') and determined that her horizons should be global. He could be stubborn and self-righteous, but he was also brave, brushing aside numerous assassination attempts, galvanising his ministers and generals at moments of crisis and stoical in the face of his descent - five times during his life - into a horrifying loss of mind.

The book gives a detailed, revisionist account of the American Revolutionary War, persuasively taking apart a significant proportion of the Declaration of Independence, which Roberts shows to be largely Jeffersonian propaganda. In a later war, he describes how George's support for William Pitt was crucial in the battle against Napoleon. And he makes a convincing, modern diagnosis of George's terrible malady, very different to the widely accepted medical view and to popular portrayals.

In presenting this fresh view of Britain's most misunderstood monarch, George III shows one of Britain's premier historians at his sparkling best.