An ‘incident’ in the Legion throws the French in the way that snow confounds the English. Yet eight thousand foreign legionnaires – the rough total – live in a permanent trough of low pressure: a sullen microclimate at odds with the parched environments in which many of them serve. In-house mythology, beamed back to the rest of us, suggests they learn to love it. But only a dark, imprisoning kind of love wants to sort the men from the boys. The lyrical jailbird Genet, whose fiction celebrates this triage, enrolled in the Legion as a young man in the 1930s. (He did a guard-house stint in Damascus.)

Unlike extreme experience designed to entertain us, the endurance of soldiers, including elites such as the Legion, needs careful positioning by the news industry to win us round. The French media can only package the Jozef Svarusko story as a scandal. Had he fallen in combat in Afghanistan, where the Legion is serving, his death would have honoured the tribe. There was honour in abundance last summer, when ten French soldiers, most of them paras from the marine infantry, were killed in an ambush in Kabul province. Sarkozy spoke of their ‘supreme sacrifice’, his foreign minister, Bernard Kouchner, talked about ‘the memory of their courage’. This affair was scandalous too – there were worries about logistical support and intelligence, and above all France’s involvement in the war – but not in the same way as Svarusko’s death.

Francophone to the last, the Legion is praised for being monocultural despite the diversity of volunteers. But the core of the organisation is French: about half, according to Tony Geraghty’s rollicking history, March or Die (1986). That figure has remained more or less steady since the 1980s, despite the recent appeal of the Legion to Latin Americans and Eastern Europeans like Svarusko.

History taught the left in France to mistrust the Legion, but the French left is now in abeyance and history talks to itself about the scratch regiment assembled at Tours in 1871, how it failed heroically to change the course of the war with Prussia, and went on with great panache to help put down the Paris Commune. The pre-independence putsch of 1961 in Algiers is better remembered: it was the Legion’s First Parachute Regiment which overran the key strategic points of the city before the generals announced that the army had seized control; four days after the putschists threw in the towel, the regiment was dissolved.

A list of nationalities (and numbers) enrolled in the Legion between its formation in 1831 and the early 1960s puts Germans well ahead of any others, including French. They and the Swiss had been the stalwarts from the early years, and it was clearly tricky for Louis Napoleon to call out the Legion to fight the Prussians when more than half the force was German. Many were stood down and replaced, for the duration, by other foreign volunteers, though German NCOs were back for the suppression of the Commune, presiding over a small force consisting mostly of Bretons.

A second influx of Germans took place at the end of World War Two. Thousands went on to fight in the French colonies. A fleeting encounter in The Quiet American alerts us to this. After a few drinks together, Fowler has followed Pyle and the US economic attaché to the House of the Five Hundred Girls. At the entrance he asks a Foreign Legion corporal whether he’s seen the two Americans. ‘He stopped cleaning his revolver and jutted his thumb towards the doorway beyond, making a joke in German. I didn’t understand it.’ Only a passing glimpse into the inner workings of colonial war – the way it sucks in fugitives and losers – yet you feel you’ve inspected the whole of the digestive tract.

In The Last Valley (2004), Martin Windrow reckons that the Legion fielded nearly 20,000 men at peak strength in Indochina. ‘The belief,’ he writes, ‘that their ranks were largely filled with German ex-Wehrmacht and Waffen-SS veterans recruited straight from French prison camps with few questions asked lent them a sinister glamour in the eyes of journalists.’ That belief was largely justified, he feels, until around 1950. By the time of the fall of Dien Bien Phu in 1954 ‘it was only among senior NCOs that Wehrmacht veterans were found in any concentrated numbers.’ Strange that they should have to taste the bitterness of defeat a second time in less than ten years. Anxious power-projectionists in the US have urged the creation of an American Foreign Legion. The American version (Armed Forces Journal, March 2007) would gulp down volunteers and spit them out with automatic citizenship after a four-year tour of duty. The idea hasn’t caught on.

An exhibition about the Foreign Legion (‘Histoires d’hommes de la Légion Etrangère’) runs until 5 April at the Val-de-Grâce military hospital in Paris. It is a cautious, self-regarding show about lives led in the Legion and famous legionnaires. As you’d expect, grizzled ex-Nazis flushing out the Viet Minh along the Red River Delta are downplayed. The Legion’s stars include the poet Blaise Cendrars, who joined in 1914, and the British ambulance driver Susan Travers, who chauffeured for a Legion medical officer in North Africa in 1941 and then, dashingly, for General Koenig, as the Free French abandoned Bir Hakeim the following year. For her gritty skills at the wheel she got membership of the Legion as a warrant officer.

Cole Porter gets top billing. What he did as a full-fledged legionnaire is much debated, but his name is on the records and he’s a great asset for the archive. In 1918, he was seconded to a gunnery regiment and won a Croix de Guerre, apparently for laying down a barrage of morale-raising songs from the barrack-room piano. In the good old days there were no Lithuanians or Letts in the Legion, but things have moved on.