The world woke up to horrific scenes of devastation on June 6: a raging torrent pouring through a gap in the dam at Nova Kakhovka, Ukraine. Russia’s invasion had produced a rich harvest of unspeakable tragedies. The breach of the dam, and the ensuing inundation downstream of Nova Kakhovka, stands in a category of its own as a grim reminder of the costs of war.

Kyiv and Moscow were quick to blame each other: the Ukrainians have accused Russia of blowing up the dam, while the Russians have cited alleged Ukrainian artillery strikes. Seeing that Russia’s occupying army was in control of the dam at the time of breach, Kyiv’s story appears more credible, though it is not yet clear whether the dam was deliberately blown up by the Russians, or whether the breach was an accident. Given that the dam failure coincided with the beginning of a Ukrainian offensive against heavily defended Russian positions, the theory of an accidental breach stretches credulity, but stranger things have happened.

The Dnieper – one of Europe’s mightiest rivers, which flows out of the murky depths of Russian forests through Belarus and finally Ukraine before it empties out in the Black Sea – has suffered such calamities before. The earlier episodes occurred during the Second World War, when first the retreating Soviet army, and then the retreating Germans, blew up dams in the hope of slowing their enemy’s pursuit.

The first time this happened was in 1941. Ukraine bore the brunt of the German invasion of the Soviet Union that summer. Just days after the invasion, the Germans captured Lviv, days later, Zhitomir, and by the end of July, Vinnytsia. Kyiv faced encirclement (its Soviet defenders would abandon the Ukrainian capital in September). By mid-August 1941, the Wehrmacht had reached Zaporizhzhia, site of the Dnieper Hydroelectric Power Station (known by its Soviet acronym Dneproges). Built in 1927-39, amid much Stalinist fanfare but to an American design, it was briefly the largest hydropower station in the world, and a celebrated symbol of socialist modernity.

It was this dam that was mined and blown up on the evening of August 18 1941, by a special team of Stalin’s secret police, the NKVD, with the use of approximately 20 tons of explosives. The explosion produced a gap in the dam, over 100 metres in length, and 20 in height. Water levels downstream briefly rose by up to five metres, inundating whole villages and drowning unsuspecting civilians.

The exact death toll is a subject of fierce contestation, with estimates of those killed in the flood ranging from thousands to tens of thousands. Whatever the case, amid the great tragedy of the unfolding war, these deaths were just a statistical footnote. There is no record to indicate that Stalin – who approved the operation – hesitated for even a moment before ordering the dam’s destruction.

Did it do him any good? Tentatively, yes: the Soviets won time, which allowed them to evacuate Zaporizhzhia, though they ultimately abandoned the city to the Wehrmacht in early October. The Germans stayed for two years, massacring up to forty thousand residents and enslaving thousands more.

In the fall of 1943, before leaving the city to the advancing Soviet armies, the Germans, too, blew up the partially restored dam.

The sad story of the Dneproges dam fits neatly in the annals of death and destruction of the Second World War. It was certainly not the worst case of man-made calamities. The 1938 destruction of the Yellow River dykes by the retreating Chinese Nationalist Army stands out as a much more severe case, with hundreds of thousands dying in the flooding and in the ensuing famine. Like the Soviets, the Chinese sought to slow the advance of the enemy – in their case, the Japanese. Like the Soviets, they were moderately successful. Like Stalin, Chiang Kai-shek disregarded the human costs, though it was his own people that paid the heaviest price.

The Dneproges dam was restored to its former glory after the war. Then, in September 1950 the Soviets decided to build another dam and an additional hydropower station, downstream from Zaporizhzhia, at a place called Kakhovka. The idea was to supply water for the irrigation of the southern Ukrainian steppe and northern Crimea, where the Soviet authorities planned to grow wheat and cotton. The massive engineering feat was completed in 1956, and since then the Kakhovka reservoir has played a key role in the regional economy, including as a source of water for Crimea.

I remember Kakhovka well. As a child, I travelled up and down the reservoir in a speed boat, living out pleasant summers in a rustic village on the left bank. Little did I imagine that Kakhovka would one day become a site of a humanitarian catastrophe.

When the Dneproges was blown up in 1941, few would have regarded it as a criminal act. Reporting on the news of the explosion on August 21, the New York Times noted merely that the dam would have made ‘an excellent bridge that the Germans might use’. There was no discussion of casualties: in the middle of a brutal war, destroying dams seemed like the thing to do.

But the law of war has advanced a great deal since then. The Additional Protocol I to the Geneva Convention (to which Russia is a party) explicitly bans attacking ‘installations containing dangerous forces’, including dams. And yet Russia reportedly mined the dam last October, probably for the same reason that the Soviets mined the Dneproges: to stop the advance of a superior army. But there is a nuance: in 1941 the Soviets mined and blew up their own dam in the territory they were defending. Today, the Russians are waging a war of aggression against a neighbouring state, making their act of ecocide (whether deliberate or accidental) so much worse.

The consequences of the failure of the Nova Kakhovka dam will not be fully known for a long time. We have little information about the situation on the left bank. What information has come through suggests widespread inundation and misery. The fact that the flooding is occurring in an active war zone will hamper relief and rescue efforts, as it also happened in 1941. Water shortages and water contamination will facilitate the spread of deadly disease. We may never know the true scale of the disaster or fully account for all of its victims.

The long-term economic consequences are hard to fathom. At a minimum, water supplies to southern Ukraine, including Crimea, will be severely disrupted, leading to a precipitous decline in agricultural yields. The entire region will suffer consequences for years and years to come.

And only the mighty Dnieper will wind its way down majestically among the hills and plains of war-torn Ukraine, irreverently oblivious to mankind’s preoccupation with building dams and blowing them up.