I rarely have reason to thank Turkish ambassadors. They tend to hold a different view of the 1915 Armenian holocaust, in which a million and a half Armenian Christians were deliberately murdered in a planned genocide by the Ottoman Turkish regime. “Hardship and suffering”, they agree, was the Armenians’ lot. But genocide? Never.

Well, that’s not the view of genocide scholars – including Israeli historians – nor of that bravest of Turkish academics, Taner Akcam, who has prowled thorough the Ottoman archives to find the proof. The Armenians did suffer, alas, a genocide.

Certainly my gratitude to His Excellency Umit Yalcin, Turkish ambassador to the Court of St James, is not for his letter to me, in which he describes the Armenian genocide as a “one-sided narrative”. But he did enclose a small book, published five years ago by Edward Erickson, whose contents obfuscate the details of the mass slaughter of the Armenians, even daring to suggest that the Ottoman “strategy of population relocation” should be seen in the contemporary setting of Britain’s policy of “relocating” civilians in the Boer War (in “concentration camps”) in South Africa, and by the Americans in the Philippines.

Interesting. But we didn’t mass rape the Boer women, burn their children and drown Boer men in rivers.

Erickson was an American army colonel and is now professor of military history at the Marine Corps University in Virginia. He insists that there was a widespread Armenian insurgency at the time of the killings. A fine Kurdish scholar has described his book Ottomans and Armenians: A Study in Counterinsurgency as “rich” in sources, but insists that these sources are distorted. Akcam himself says that even if Erickson’s contention that there was a real Armenian insurgency in Turkey (which Akcam disputes) was true, this would only explain why the genocide happened – not why it never occurred!

But what fascinated me in Erickson’s book was a chapter which probably held little interest for Ambassador Yalcin – but which should be both grim and prescient for Crown Prince Mohammad bin Salman of Saudi Arabia. This chapter is contained in a mere eight pages. But it describes a continuous, costly, bloody and hopeless war between the Zaidi tribes of Yemen and the Turkish Ottoman forces loyal to Constantinople in the late 19th and early 20th centuries. The Houthis – of present-day Yemeni military history – belong to the Shia Zaidi, a branch of the Shia imamiyah of Iran. And the Zaidis, in their battle against the Ottomans, acquired new and sophisticated weapons. The Ottomans attacked a port called Hodeida. There was famine across the land. Does this sound rather familiar?

And bad news for the Saudis who – as near as history would permit these days – are now playing the role of the Ottomans slightly over a century ago, trying to suppress a local Shia rebellion in their sphere of interest with the most expensive of weapons and the most costly of training that money can buy; and with the hubris of an Ottoman power which thought it wielded the strongest military force in the Middle East. By now, I think that Ambassador Yalcin probably realises just why I really am grateful to him for sending me this book. Even more so when I add that the Ottomans were forced to end their wars in Yemen with what now faces the region’s leading Saudi warlord: a negotiated settlement.

Historical precedents are never exact. Unlike the Saudis, the Ottomans had no major power to support them in their Yemeni adventures. And of course, they had no air force. The Zaidis were closer to their Sunni co-religionists than the Saudis might accept today. Over centuries, they prayed in the same mosques. But the story of a large and cumbersome Ottoman army floundering around the deserts and mountains of Yemen, pursuing tough and resilient rebels while other major wars loom far to the north has a frightening contemporary relevance.

The ruthless Ottoman military governor Feyzi Pasha suppressed a Yemeni rebellion by Imam an-Mansur in the late 19th century with modern counterinsurgency tactics – with small columns of men and what Erickson calls “devastating European-style firepower superiority”. But the Turks ran out of money to improve the lives of Yemenis. By the early 20th century, Ottoman control was vested in a small 18,000-strong army headquartered in Sanaa. Another rural rebellion began in 1904 under the imam’s son, and within a month the Zaidis had blocked the road between Sanaa and the port of Hodeida. Telegraph wires were cut, caravans suspended and Sanaa put under siege. The rebels themselves had acquired new magazine-fed military rifles. The Ottomans brought in more troops from around the empire – from Macedonia, Albania and, interestingly, Arab units from Syria.

Ottoman reinforcements under Riza Pasha were repeatedly ambushed by the rebels. Turkish morale collapsed. Some of the Arabs in the Ottoman army turned out to be sympathetic to the Zaidi rebels – could they, perhaps, have been Shiite or Alawite Syrians? We do not know.

Thousands more troops arrived to crush the rebellion, but Sanaa was already lost. Then the Ottomans needed to withdraw many of their troops for other campaigns within the empire. As Erickson writes, “the campaign turned into a quagmire for the Ottoman Empire and the Syrian units of the expeditionary force began to mutiny”. Out of 110,000 Ottoman soldiers, casualties stood at more than 25,000 by 1905.

Turkey’s Yemen war turned into a history of ceasefires and negotiated truces while the Turkish Ottoman army had to be reformed in order to survive, with a new officer corps and an end to patronage – not dissimilar to princely patronage in the present-day Saudi military. But the Ottomans were unable to crush yet another insurrection which only ended in 1912. And within two years, the First World War distracted – and then ultimately destroyed – the entire Ottoman Empire.

Thus while the Ottomans remained an imperial power at the end of their Yemen war, their prestige and morale had drained away in this outpost of empire. They squandered their resources in annihilating the Armenians in 1915 and finally collapsed before Allenby’s advancing armies in 1918. No, history is not exact. Once the British-supported Arab Revolt began in 1916, for example, Yemen was effectively cut off from its notional Ottoman masters. The future “empire” in the Arabian Peninsula would be controlled first by the Hashemites and then by the House of Saud.

Which brings us back to Saudi Arabia and its own self-destructive, useless war with the rebels of Yemen, the descendants of those same Zaidi tribes which so humiliated the Ottomans. It was Mohammad bin Salman who launched this conflict – which is supposed to protect the Sunni world from the Shiites of Iran and its allies – and he will be held responsible for its disasters. He has allowed the United Arab Emirates to do the fighting on the ground. What we do not know – and what the west does not want to know and does not ask about – is the effect of this disastrous campaign on the armies of Saudi Arabia and the Emirates.

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While the Saudi crown prince now fritters away his time trying to salvage his own personal prestige from the disgrace of the Khashoggi murder, what are his generals thinking about their military prestige? The Saudi National Guard, the king’s private army, and the Saudi armed forces – all, of course, loyal, trustworthy, patriotic chaps, so we are told – can only be deeply upset at the course of the Yemeni war. If the Ottomans could be humiliated by Yemeni rebels, have not the Houthis shamed and humbled the armed forces of Saudi Arabia?

What do the warriors in the Royal Saudi Air Force think – after firing their bombs and missiles at the puny forces of “Houthistan” – when their enemies are now negotiating a peace in a Swedish town called Rimbo? If the Ottomans had to reform their army, what is to be done with the Saudi military? The crown prince thinks he can reform his kingdom’s economy. But his soldiers may have to reform themselves. An end to patronage, perhaps? A new officer corps? Now there’s an Ottoman precedent to bear in mind. Could the crown prince survive that?

I don’t trust Erickson’s analysis of the Armenian genocide. Nor that of the Turkish ambassador to the Court of Saint James. But I thank them both for the ideas that a small book on the Ottomans contains about Yemen. Maybe it should be essential reading in Saudi military colleges. In the King Abdul Aziz Military Academy and the King Khalid Military Academy, perhaps.