The daring 1971 thriller “The French Connection” is a great film whose storied production has made it a Hollywood legend. The improbable winner of five Academy Awards, the movie seemed charmed by outrageous good luck and came to life thanks to the unorthodox, sometimes reckless methods of director William Friedkin.

The picture was based on the exploits of real-life New York narcotics detectives Eddie Egan and Sonny Grosso (renamed “Popeye” Doyle and “Cloudy” Russo for the film), who themselves benefitted from extraordinary luck. Out for a drink at a nightclub one evening, they saw a man spending lavishly. Suspicious, they followed him, eventually discovering he was the American contact for a notorious French drug kingpin who had eluded cops for years. Their rough tactics and obsessive pursuit of this “French connection” soon made them legends in the NYPD.

Shooting on the streets of New York on a woefully inadequate budget, Friedkin didn’t bother with time-consuming and expensive permits and security arrangements. He arrived at a location, used available lighting, and captured virtually everything in one or two takes.

To enhance the documentary feel of the movie, Friedkin kept his camera operator away from the location until everything was planned out. The operator then shot the scene with no foreknowledge of what was about to happen. The resulting camera work was grainy and frenetic, giving the picture a look that was jarring and unnerving for 1971 audiences.

Casting was also marked by good fortune. After failing to get any of his top choices to play Popeye Doyle, Friedkin was “stuck” with Gene Hackman, who he thought was wrong for the part. On the disastrous first day of shooting, the mild-mannered Hackman couldn’t bring himself to rough up the drug-dealing character he was playing opposite. He nearly quit that day and Friedkin nearly let him. But soon, Hackman and co-star Roy Scheider were dazzling Friedkin, Egan and Grosso with their gritty, realistic performances.

The casting of the French drug kingpin was a complete accident. Friedkin asked his producer to hire Spanish actor Francisco Rabal for the role. The producer mistakenly hired a different Spanish actor, Fernando Rey. Friedkin thought the urbane Rey was all wrong, but his elegant villain ended up providing a stark contrast to Hackman’s rough, streetwise, often unlikable hero.

But the picture’s greatest luck was reserved for the legendary chase scene. Friedkin had completed all of his planned shots for the sequence, but was unhappy with the result. He openly challenged the talent of his stunt driver, goading him into undertaking a reckless ninety mile-an-hour drive through twenty-six blocks of New York City traffic.

With no planning, no permits, and no police protecting the route, it’s miraculous that no unsuspecting driver or pedestrian was hurt or killed during the stunt. That shot forms the backbone of what many consider to be the greatest chase scene ever committed to film.

Hackman and Scheider both went on to brilliant careers, but Friedkin was not so lucky. His next film was the wildly successful “The Exorcist.” But in 1977, he directed “Sorcerer,” a box-office disaster that nearly ended his career. He’s gone on to direct many films since, but never again reached the dizzying heights he achieved in his early-'70s masterpieces.