It was 75 years ago, a couple of decades before I was born, but I remember every detail. The Germans wore gray, she wore blue.

Any time anyone asks me to name my favorite movie of all time — an occupational hazard for a movie critic — I answer “Casablanca,” which had its premiere on Nov. 26, 1942, in New York and opened nationwide in January 1943.

I choose “Casablanca” as my lifetime No. 1 movie over a lot of the usual suspects — “Citizen Kane,” “Vertigo,” “The Searchers” or some European master’s classic — for a lot of reasons, some well thought out and others strictly emotional.

“Casablanca,” for me, represents the finest hour for Hollywood’s old studio system. It was one more title in Warner Bros.’ pipeline and could have ended up as forgettable and forgotten as most of the studio’s product. Somehow — thanks to some producing pluck, smart writing, star power, a sharp director and some lucky breaks — it emerged as a truly special movie, still immensely entertaining years later.

Set in early December 1941, just days before the Japanese attacked Pearl Harbor, the story — adapted from an unproduced stage play, “Everybody Comes to Rick’s,” by brothers Julius and Philip G. Epstein and Howard Koch — takes place in ostensibly neutral French Morocco. The territory is overseen by the Vichy regime, a puppet of the Germans, and the city of Casablanca has become a way-station for people trying to escape the spreading Nazi control of Europe.

The one truly neutral zone in Casablanca is Rick’s Cafe Americain, run by a shady expat, Rick Blaine (played by Humphrey Bogart). Like the United States at the time, Rick doesn’t take sides. “I stick my neck out for nobody,” he says early in the film. Later, he tells some patrons, “Either lay off the politics or get out.”

The Epsteins and Koch give us plenty of hints about Rick’s backstory, but no clear picture. Casablanca’s jovially corrupt Prefect of Police, Capt. Louis Renault (Claude Rains), speculates on why Rick had to leave America. “Did you abscond with the church funds? Run off with a senator’s wife? I like to think you killed a man. It’s the romantic in me.” We also learn he ran guns for anti-Fascists in Ethiopia and Spain, and though he insists he did it for money, Renault points out, “The winning side would have paid you much better.”

On one particular night, some important guests visit Rick’s. One is a high-ranking German officer, Major Strasser (Conrad Veidt), who’s on the trail of a famed Resistance leader, Victor Laszlo (Paul Henreid). The other two are Victor and his wife, Ilsa Lund (Ingrid Bergman) — who, we learn, is that one woman from Rick’s past whom he could never put out of his mind.

“Casablanca,” then, becomes that rare movie with two leading men both pursuing the same woman — and neither is the heel. The fact that the story could have gone either way is probably what prompted the urban legend that the ending was in doubt all the way to filming. The script was unfinished, something that rankled the Hollywood neophyte Bergman, but the idea of which man she’d end up with was never in doubt.

That wasn’t the only urban legend “Casablanca” spawned. For example, it was never really true that Ronald Reagan was considered for the lead role of Rick Blaine, though he was mentioned once on a studio press release. (Ann Sheridan, however, was an early pick to play Ilsa, before producer Hal B. Wallis persuaded mogul David O. Selznick to loan out Bergman.)

So much of what went into “Casablanca” was dictated by Warner Bros. standard operating procedure. Bogart and Henreid were contract players, as were character actors Peter Lorre and Sydney Greenstreet (both of whom Bogart worked with on “The Maltese Falcon”) and Rains. Warner Bros. also had director Michael Curtiz, a Hungarian emigré who had helmed Errol Flynn in a host of films and James Cagney in “Yankee Doodle Dandy,” among many other films.

The real star of “Casablanca” was that script, with so many quotable lines, most of them given to Rains’ Capt. Renault. “I’m only a poor, corrupt official.” “I’m shocked, shocked to find that gambling is going on in here” (just before he’s handed his winnings). “Round up the usual suspects.”

“Casablanca” won three Academy Awards — for Best Picture, for Curtiz’s direction, and for the screenplay. How Bogart and Rains missed out on Oscars is an enduring mystery. (Bogart lost to Paul Lukas for “Watch on the Rhine,” but won in 1951 for “The African Queen.” Rains was nominated for supporting actor but lost to Charles Coburn for the forgettable wartime comedy “The More the Merrier”; it was one of four nominations for him in the 1940s, but he never won.)

What I love about “Casablanca” is that it defies categorization into any single genre. It’s a war movie, a spy movie and a romantic drama, laced with bracing humor. It’s also lovingly patriotic, as when Victor leads the bar in the French anthem “La Marseillaise,” without being pandering.

The fact that a major studio made “Casablanca,” almost entirely on its own sets and backlots, like one more widget off the assembly line, is something of a miracle. If you’ve never seen it, make the effort — it will be the beginning of a beautiful friendship.