Nearly four months on from the Gaza conflict, the image I remember most is this: we are in the crowded triage room at Al-Shifa hospital, whose tiles are echoing with wails and screams. A group of men is staring at a pile of curtains, blankets and towels on the floor. Then somebody uncovers what’s beneath.

If you watched TV reports that night you would have seen the blurred bodies of six children. My cameraman took a shot of blood being mopped off the floor to signify what we could not show.

But on Twitter they don’t blur things out. If you follow the Syrian conflict, you will see horrific pictures of dead children and their grieving relatives several times a week. If you’re following the Islamic State story on social media, you will see crucifixions, executions, beheadings – often posted by people trying to convince us that IS are bad and should be blown to smithereens themselves.

We are besieged now by images of the dead in conflict, usually published by people who believe it will either deter killing, expose the perpetrators or illustrate war’s futility and brutality.

It is an old illusion and we can trace it back to a precise moment in history. In 1924, the German anti-war activist Ernst Friedrich published a shocking book called War Against War!.

Friedrich had been jailed during the war for sabotaging production in an arms factory, and was a wild leftwinger. By the early 1920s, he had assembled a comprehensive collection of photographs showing the reality of the first world war. Probably the most offputting are those of facial mutilations endured by surviving soldiers.

But there is also documentary evidence of the brutalities of war: the hanging of a priest by a triumphant German soldier; a starved Armenian child, captioned by the words of a German politician who had claimed that “every mercy shown to lower races is a crime against our mission”.

Often Friedrich himself indulged in crude propaganda: a picture of “Papa” posing proudly in his uniform on recruitment, juxtaposed with his shattered body three weeks later, with the comment “not included in the family album”.

Though hounded by censors and lawsuits, Friedrich’s book went into 10 editions before the Nazis banned it. The “international anti-war museum” he had opened in a terrace house in Berlin was closed by Hitler’s stormtroopers in 1933 and turned into a torture chamber.

Friedrich’s work represented a breakthrough. Before then, imagery of war had been subject to absolute censorship during conflict and diluted for the sake of “taste and decency” by the media during peacetime.

So War Against War! – republished in facsimile this year in the UK by the Bertrand Russell Peace Foundation – poses a relevant question: why is it that showing people gruesome photographs of war injuries does not deter war? In a conflict such as Israel-Palestine, people on both sides feel compelled to fight. Other conflicts are wars of choice. Professional soldiers know what they are signing up to. One day spent on a trauma first aid course, even with fake blood spurting out of rubber prosthetic wounds, is enough to illustrate what it is going to be like.

The closer I get to conflict, and the people who endure it, the more I think: nothing we know about war can deter us from it. In fact, in the 90 years since Friedrich’s book came out, we’ve developed coping strategies to assuage the feelings of horror such imagery arouses.

Faced with horrific injuries, we develop prosthetic technologies and plastic surgery. Faced with lethal weaponry – we develop Kevlar or drones and stand-off weapons to keep our own soldiers safer. We professionalise armies and improve survival rates for the wounded.

Plus there’s international law. Today, no day of conflict passes without somebody accusing someone of breaking the Geneva Conventions. The implication is that war conducted according to the rules is regrettable but all right. Instead of the language of the jingoist, which Friedrich ridiculed, we have the language of the technocrat: collateral damage, civilian deaths to be regretted.

Finally, while the first world war was begun in ignorance about the horrors of war, by the mid-century, belligerents had learned how to use images of atrocity to fire people up to fight.

But why do we then report war? Last week, I attended the Rory Peck awards, where my Gazan producer Khaled Abu Ghali won the Martin Adler prize for the work he did for Channel 4 News. The room was full of people who risk their lives to get pictures of horrific injury, cruelty and death, and the executives who send them there.

There’s a growing frustration in this milieu not just that journalists are being targeted, but that a disbelieving public has come to see all graphic imagery of war as potentially fake, manipulated or propagandist.

Adler, a Swedish film-maker murdered in Mogadishu in 2006, imbued his camerawork with an unflinching gaze. It was the absurd human situations, the disarmed honesty of the combatants and pointlessness of conflict that he was there to record, not the mutilated faces.

Many Germans in the 1920s and 30s came to believe, despite the horrific photographs, that the war had embodied the noblest and most exhilarating aspects of human life; and specifically that warfare represented the ultimate in technological modernity and moral freedom. This remains a more dangerous myth than the idea that war is harmless, fun or simply heroic. Adler, and others like him, understood that showing absurdity is more important than showing injury.

I have no doubt the men clustered around the children’s bodies in Al-Shifa thought the war they were fighting was just. But the collective sigh when they saw the injuries convinced me they had seen through any illusions as to the conflict’s glory.

Pictures of war should not only show us what bodies look like. They should educate us about the absurdities, the accidents and pointless killing.

Paul Mason is economics editor at Channel 4 News. Follow him @paulmasonnews