Great Catastrophe: Armenians and Turks in the Shadow of Genocide. By Thomas de Waal. Oxford University Press; 298 pages; £18.99.

ON APRIL 24th millions of Armenians around the world will commemorate the centenary of the mass killing of their forebears by Ottoman forces. A growing number of historians say it was genocide.

“The central facts of the story are straightforward,” says Thomas de Waal, a Russophile scholar at the Carnegie Endowment for International Peace, an American think-tank, in the introduction to his objective and meticulously researched account of the Armenian tragedy and how it has played out in modern times. “The Armenians were an ancient people, whose homeland was centred in what is now eastern Turkey.” In 1913, there were up to 2m of them in the Ottoman empire. At the start of the first world war, the Ottoman government ordered their mass deportation. A few years later, Mr de Waal writes, there was barely one-tenth of that number in Turkey. The rest had been exiled or killed.

A plethora of academic tomes, memoirs and novels about the genocide exist, including Turkish government-sponsored propaganda purporting to prove that most of the Armenians died of hunger and disease during their forced march to the Syrian desert in 1915. Mr de Waal navigates through some of these. Yet, unlike many, he does not set about legislating history. Rather he offers the wider context in which what Armenians call Meds Yeghern, or the “great crime”, unfolded. (He uses the term “great catastrophe”, which has riled many.)

Abdul Hamid II, who became the Ottoman sultan in 1876, was consumed with paranoia as he watched his empire shrink. He accused his Armenian subjects of plotting with the great powers to truncate it further and unleashed a first wave of pogroms, which claimed nearly 100,000 lives. Armenian revolutionaries retaliated by killing Ottoman officials and siding with “Uncle Christian” (Russia) as it gobbled up chunks of eastern Anatolia. (The Armenian relationship with Russia is a constant thread.) Decades later a different group of Armenian “revolutionaries” embarked on a revenge killing spree of Turkish diplomats from Vienna to Sydney.

Mr de Waal’s biggest contribution is his overview of the interlocking phases of Turkish and Armenian history after 1915. Trenchant and colourful anecdotes abound, along with some surprising facts. The Ottomans were the earliest to recognise the first and short-lived Republic of Armenia in June 1918 (it collapsed two years later under Soviet pressure). Three months afterwards the Ottoman military commander, Halil Pasha, who personally directed massacres of Armenians and Assyrian Christians in the eastern provinces, met the Armenian interior minister in the capital, Yerevan. “The two men had fought a battle to the death in Van in 1915”, yet they “kissed each other warmly like friends.”

Turkey was again among the first to recognise the fledgling Republic of Armenia when it broke away from the Soviet Union in 1991. But before diplomatic ties were formally established Armenia went to war against Turkey’s ally, Azerbaijan, over Nagorno-Karabakh, a mainly Armenian enclave in Azerbaijan. (Mr de Waal’s book about that conflict, “Black Garden”, is an important complement to this one.) Turkey sealed its border with Armenia and so it has remained, leaving the tiny landlocked nation ever more dependent on Russia. Swiss-brokered interventions collapsed when Turkey, buckling under Azerbaijani pressure, shelved an agreement from 2009 that would have established diplomatic ties and reopened the border. The author’s vivid description of the backroom dealings that went on helps explain why.

Mr de Waal reluctantly concludes that the killings do come under the United Nations Convention on Genocide. He believes the “G-word” (this last term was coined by a Turkish diplomat) has become “both legalistic and over-emotional”. It obstructs “the understanding of the historical rights and wrongs…as much as it illuminates them”. But according to Hrant Dink, a Turkish-Armenian newspaper editor killed in 2007 by a young ultranationalist, Turkey’s main problem is not whether it should deny or acknowledge that what happened amounted to genocide, but what its people comprehend. That is true, but only up to a point. Turkey has recently begun making conciliatory gestures to the Armenians. That would never have happened had the world, and especially America’s Congress, not held the possible charge of “genocide” over it.