Joanna Bourke: It's a game ... until blood is spilt

The romance of war should never be underestimated. Terms like baptisms of fire, transfigured youth, and gallant warriors are endlessly repeated in the media once war is declared. Language becomes perverted. Speech becomes ritualised, and the distinction between what is and what ought to be fractures. British pilots become "knights of the sky" while infantrymen are transformed into "chivalrous warriors".

The glamour of fit young men posing on exotic battlefields next to gleaming weaponry has an almost pornographic appeal. The mechanical elegance of M-60 machine guns are described in seductive tones, just as decorated swords were in the medieval period. Servicemen can be heard calling their weapons "beautiful", even "sexy". In the words of the soldier-poet Jack Strahan, bombs are "more thrilling than an earthquake. When hit with their obscene blast wave, you laugh, not knowing war could be such fun". Despite a grotesque disparity in weaponry, combat is spoken about as a romantic adventure or duel. The fate of the enemy is minimised: they are animals – baboons, vermin, wild beasts – or simply shadows on a radar screen.

The romanticisation of war can work well far from the battlefields. In the past, women's experience of war has been primarily concerned with persuading men that dishonour is worse than death, and then buckling on men's psychological (if not military) armour.

It is easy to understand how "action" is deeply desired by servicemen recruits. During the Second World War, many British servicemen were so eager to fight that, if delayed, they burst into tears. Observers at the time said these men's mind were "full of romanticised, Hollywood versions of their future activity in combat, coloured with vague ideas of being a hero and winning ribbons and decorations". Their notion of war was framed by heroes such as Douglas Fairbanks, Errol Flynn, John Wayne and Gary Cooper.

These images were so powerful that many servicemen found themselves attempting to re-enact them "in real life", termed "the John Wayne syndrome" in the military. In other words, war was a version of cowboys-and-Indians. In the invasion of Grenada in 1983, American soldiers charged into battle playing Wagner, imitatingRobert Duvall, the brigade commander in Apocalypse Now. The famous war correspondent Michael Herr said soldiers "were actually making war movies in their heads, doing little guts-and-glory leatherneck tap dances under fire, getting their pimples shot off for the cameras".

Disillusionment was swift. Men were not prepared for the horror of being ordered to fire on unarmed or surrendering enemy troops and civilians. They vomited at the stench of blood. Dehumanising the enemy was easy in rehearsals on the Sussex Downs; not so straightforward in battle. Combatants were forced to recognise that "we were out there fighting because we were told to, and they were out there fighting because they were told to". Furthermore, languages of chivalry and fair play crumbled: long-distance artillery, sniping, orders not to take prisoners and unequal opponents were the norm in modern warfare, not exceptions. Attempts to make combat conform to expectations were risky. Acting like John Wayne cost lives. In the words of one British pilot during the First World War, it was lucky that the "big bugs" kept them busy between forays because "when I start to think of it I start to drink". Or, as a former US soldier in Vietnam confessed: "We were invincible ... everyone went in with the attitude of 'Hey, we're going to wipe them out. Nothing's going to happen to us.' Until they saw the realities and they couldn't deal with it. For combatants, the real "baptism of fire" was impossible to convey to family and friends back home. The exhilaration of anticipating combat, followed by the terror of possibly dying was too often simply unspeakable. Today, the gung-ho enthusiasm of British troops awaiting action is reverberating loudly: the other, more painful emotions that have accompanied battle in the past have yet to be experienced. But that is what awaits our troops.

Joanna Bourke is Professor of History at Birkbeck College and author of 'An Intimate History of Killing'