On a warm evening in a French seaside town, casually dressed pedestrians throng the length of an elegant promenade, filling its restaurants and bars. Suddenly, an ambulance speeds down the road, its siren cutting through the chatter. The rear doors are flung open and a white object is thrown into the street. It’s the corpse of a doctor, who’s been stabbed. The occupants of the ambulance then start shooting at the crowd, before hurtling at top speed into a group of people sheltering at a bus stop.

The scene, grimly reminiscent of the terrorist attack in Nice this summer, is the opening to Gillo Pontecorvo’s film “The Battle of Algiers”. First released 50 years ago this autumn, it recounts the central episode of the eight-year guerrilla war waged by the resistance fighters of Algeria’s National Liberation Front ( FLN ) against the French colonial regime. What begins as an amateurish insurgency by a couple of unemployed youths explodes into full-scale urban warfare. The French administration sends in the army to quell the disturbances but only succeeds in making the situation worse: bombs are planted in bars, suspected terrorists are rounded up and tortured and innocent people are shot in the street. Having razed large parts of the city to the ground and alienated even the least politicised Algerians, the French army triumphs – but their victory is a hollow one. Within two years, the French are forced out of Algeria.

“The Battle of Algiers”, which the academic and critic Edward Said described as one of the greatest political films ever made, was controversial as soon as it came out. With its pseudo-documentary style and frank depiction of guerrilla tactics, it could almost be a manual for would-be terrorists. Indeed, the Baader-Meinhof gang were reportedly big fans. It was famously banned by the French government. In 1966, the country was still coming to terms with its withdrawal from Algeria four years earlier, and the authorities were worried that the film – backed by the Algerian government and apparently sympathetic to the Algerian side of the story – might inspire outbreaks of revanchist violence. Far-right groups were all too prepared to blow people up in retaliation for what they saw as the betrayal of l’Algérie Française and its million European settlers, most of whom fled to France after independence.

Four decades later, the film would become notorious for a different reason. Soon after the American-led coalition’s invasion of Iraq in 2003, the Pentagon held a special screening for officers and military experts, presumably so they would learn from the mistakes made by the French army. The film, explained the organisers of the screening, showed how a country could “win a battle against terrorism and lose the war of ideas.”

It would be a shame if the controversy associated with “The Battle of Algiers” obscured how accomplished it is. Unlike other political films of the era – for instance, Jean-Luc Godard’s film about the Algerian war, “Le Petit Soldat”, with its voguish philosophical discussions – it has not dated a bit. From Ennio Morricone’s pacy, minimal soundtrack of piano and marching drums to the sparse but memorable script, it still feels fresh.

Remarkably, all the actors bar one – Jean Martin, who plays the philosophical paratroop commander Colonel Mathieu – were amateurs. Yet nothing feels awkward or stilted. Dialogue is kept to a minimum and a newsreel-style voiceover plugs any gaps in the narrative.

The two stand-out performances are by Brahim Hadjadj, who resembles a Maghrebi James Dean as the petty-criminal-turned-guerrilla-fighter Ali La Pointe, and the casbah itself. Vertiginous tracking shots wind down its steps and narrow alleyways, following camouflaged French paratroopers as they chase teenaged guerrillas in a bloody game of cat and mouse. Interior scenes are cramped and dingy, the grainy black-and-white cinematography adding to the sense of claustrophobia. The film is so full of suspense it makes “Vertigo” look slack. Female FLN members – disguised as fashionable French women – chew their fingernails to stubs waiting for the bombs they have hidden in the cafés and milk bars of the European quarter to detonate.

Pontecorvo’s film could so easily have become a simplistic hagiography of the Algerian independence struggle, yet nobody comes out of it well. The violence carried out by the FLN is horrifying: policemen are executed at random on quiet pavements and collaborators are assassinated. Both sides make repeated attempts to justify what they’re doing, often with a chillingly eloquent rationale: “Should we [the French] remain in Algeria?” asks Colonel Mathieu at a press conference, trying to make the case for the use of torture. “If you answer ‘yes,’ then you must accept all the necessary consequences.” Yet the competitive savagery of their attacks makes their grandiose claims seem as hollow as the false walls in which the FLN hide out from the French army.