The bombing attack on Dresden, Germany, stands among the most controversial Allied actions of World War II. From February 13 to 15, 1945, 800 bombers dropped some 2,700 tons of explosives and incendiaries, decimating the German city. Tens of thousands died.

American prisoners of war had heard the “whump a whump” of distant aerial bombings many times before. But on February 13, 1945, they heard Dresden’s fire sirens howl right above their heads. German guards moved them two stories down into a meat locker. When they came back to the surface, “the city was gone,” remembered writer and social critic Kurt Vonnegut—one of the American POWs who witnessed the Dresden bombing.

Since Dresden served as a major center for Nazi Germany’s rail and road network, its destruction was intended to overwhelm German authorities and services—and to clog all transportation routes with throngs of refugees. The Allied assault came less than a month after some 19,000 U.S. troops were killed in Germany's last-ditch offensive at the Battle of the Bulge, and three weeks after the grim discovery of the atrocities committed by Nazi forces at Auschwitz.

In an effort to force a surrender, the Dresden bombing was intended to terrorize the civilian population locally and nationwide. It certainly had that effect.

In the time that Vonnegut and others hid underground, the British Bomber Command’s Blind Illuminator aircraft had rained explosives and incendiaries over the city. Then, “visual marker” aircraft swooped low to drop thousands of flares and fire-target markers. The main attack formation followed: over 500 heavy “Lancaster” bombers loaded with explosives and incendiaries. The U.S. Eighth Air Force attacked the next day with another 400 tons of bombs and launched yet another raid with 210 bombers on February 15.

With the German Luftwaffe destroyed and anti-aircraft defenses in shambles, the Royal Air Force lost only six planes. On the ground, however, thousands of small fires merged into a powerful firestorm that created such powerful winds that it sucked oxygen, fuel, broken structures and people into its flames.

“Those who have unlearned how to cry,” lamented Nobel Prize recipient and Prussian dramatist Gerhart Hauptmann, “will learn it afresh on the destruction of Dresden.”

Initial—and partisan—estimates of the number of dead seemed to suggest that the Dresden Bombing was uniquely cruel. David Irving would claim in his 1963 book, The Destruction of Dresden, that the bombing was “the biggest single massacre in European history.” His estimate of 150,000 to 200,000 dead was long accepted without dispute. But his assertion that Dresden was the “Hiroshima of Germany” quickly drew serious criticism, not just for its lack of evidence, but also for ignoring the Holocaust. (Irving later earned notoriety—and a criminal conviction—as a Holocaust denier.)

In part to prevent right-wing ideologues from exploiting widespread speculations about the death toll, the city of Dresden set up a historical commission in 2004 to produce more precise data with historical, military, forensic and archeological research. In 2010, it published a revised estimate of 22,700 to 25,000 dead.

As shocking as such an enormous number of dead is, it did not stand out in the war’s history of “strategic bombing” of cities. Most German cities had been flattened by 1945, and many left higher proportionate death rates and degrees of destruction. The bombing of Hamburg in July 1943 generated the first large firestorm and killed more than 30,000 civilians. And while the German Blitz over England became the subject of many books and movies, the Luftwaffen raids on Eastern European cities such as Belgrade (more than 17,000 dead) or Warsaw (up to 25,000 dead) were far more deadly—to say nothing of non-nuclear city bombings in Japan.

On the ground, however, the scale of death and devastation seemed beyond compare to witnesses like Vonnegut.

Assigned to a sanitary clean-up crew after the bombing, POW Vonnegut had to dig into shelters and basements which “looked like a streetcar full of people who simultaneously had heart failure. Just people sitting in their chairs, all dead”—robbed of oxygen by the all-consuming firestorm.

Observers noted early on that the bombing of Dresden not only meant the death of civilians but the destruction of a center of European culture and Baroque splendor. Since the rule of August the Strong (1670-1733), the “German Florence” on the Elbe, was home to famous collections of art, porcelain, prints, scientific instruments and jewelry.

Many Germans perceived a particular injustice in the late bombing of Dresden in February 1945—a sentiment that gained some international traction in the postwar years. Dresden was a densely crowded city in the winter of 1945, filled with refugees fleeing the advancing Red Army. For most of them, the end of the war looked near and inevitable and a full-scale attack was unnecessary.

Allied strategists, however, were afraid of allowing the Wehrmacht to regroup within Germany’s border if they eased on their pressure. The U.S. Army alone had suffered almost 140,000 casualties from December to January 1945 and 27,000 in the week prior to the Dresden bombing alone—the heaviest losses in the Western Allies’ war against Hitler.

So while the Dresden bombing was a terror campaign that dealt a devastating assault on civilians and cultural sites, it was part of a war in which such tactics had been widely—and grimly—deployed. Less than three months later, and eight days after Adolf Hitler committed suicide in his underground bunker, the German High Command signed the unconditional surrender of all German forces.