Among the books my children enjoy are the Horrible Histories, a series of light-hearted introductions to historical subjects with titles like The Rotten Romans, The Terrible Tudors and The Vile Victorians. If their creator, Terry Deary, lacks the time or inclination to write The Bloody British Empire, he can subcontract the job to Johann Hari.
In his column on Monday ("There can be no defence for empire", 12 June), Horrible Hari simultaneously misrepresented my work and caricatured to the point of absurdity the history of British imperialism. I pass over the strange charge that I am "court historian for the imperial American hard right". Anyone who has read my book Colossus: The Decline and Fall of the American Empire will know how laughably wide of the mark that is.
More intriguing is the claim that I "consistently underestimate or ignore the massive crimes of Empire, and grossly overstate the benefits". Two examples of "crimes" supposedly glossed over in my book Empire are cited. According to Hari, Britain engaged in "a conscious policy of mass starvation of Indians in the 1870s and 1890s". This, he argues, was "a crime worthy of Stalin and Mao".
Less than a century later, in the 1950s, the British also "herded more than 300,000 Kenyans into gulags to be whipped, castrated and raped" during the Mau Mau "Emergency". "More than 50,000", he asserts, were "slain".
The article would appear to be based on two books: Mike Davis's Late Victorian Holocausts: El Nino Famines and the Making of the Third World, and my Harvard colleague Caroline Elkins's Britain's Gulag: The Brutal End of Empire in Kenya. As their titles suggest, both books make explicit - and sensationalist - comparisons between British imperial rule and the totalitarian tyrannies of the mid-20th century.
There is, however, an essential difference between the famines that were a recurrent problem in British (and Mughal) India and wilful genocide of the sort perpetrated by Hitler against the Jews during the Second World War. And there is also a huge difference between the response of the authorities in Kenya to a violent insurrection and the Soviet system of slavery and terror.
No one disputes that Victorian officials in India were ill-equipped to mitigate the effects of famines. In the case of Lord Lytton, Viceroy during the disaster of 1876-8, there is clear evidence of incompetence, negligence and indifference to the fate of the starving. But to equate Lytton with Himmler is absurd and offensive.
A more valuable account by far is Tirthankar Roy's recent Economic History of India, 1857-1947. Among other things, Roy shows there was a sustained improvement in the mortality rate in India between the 1880s and the end of British rule. There was no famine after 1900 until the war-induced disaster of 1943.
It is equally egregious to compare the suppression of Mau Mau with Stalin's Terror. No one disputes that the authorities in Kenya used exceptional violence during the 1950s. But the point, as David Anderson writes in his meticulous Histories of the Hanged: The Dirty War in Kenya and the End of Empire, is precisely that it was exceptional. "In no other place, and at no other time in the history of British imperialism," he writes, "was state execution used on such a scale as this." To be precise, 1,090 Kikuyu were hanged for Mau Mau crimes, out of around 150,000 who were detained at one time or another during the crisis. Between 12,000 and 20,000 rebels were killed in combat, for this was a civil war in which the rebels killed at least 1,800 African civilians, 200 British soldiers and policemen, and 32 European settlers.
For the record, estimates for the total victims of Stalin range from 9 million to 51 million. Mao's reign of terror is said to have killed between 20 and 75 million people. Even if Hari's figures for Mau Mau dead were not inflated, they would still be around three orders of magnitude smaller. Britain's Gulag? Read some Solzhenitsyn if you still don't get the difference.
According to Hari, I have argued that "there are great swaths of humanity inherently incapable of self-rule who must be forever subject to imperial masters". This is wrong. In Colossus I argued that a small number of failed states and rogue regimes would only stand a chance of becoming democracies if there were temporary suspensions or limitations of their sovereignty.
The point that I make in The War of the World is that one of the main reasons for the extreme violence of the 20th century is that so many empires declined and fell in the period. It is an empirically verifiable fact that violence tends to increase as empires unravel, as indigenous ethnic groups compete, often violently, for future shares of power. The peak of violent death (as opposed to death by starvation) in modern India was of course in 1947, as the British withdrew and Hindus and Muslims slaughtered one another.
Hari calls, in a somewhat sinister phrase, for an "act of intellectual hygiene". It is, however, he who must come clean. His Horrible History is about as serious as the latest product of Terry Deary's pen.
Niall Ferguson new book, The War of the World: History's Age of Hatred, has just been published by Penguin Books