What is it? A Wartime tale of refugees escaping Occupied Europe through the titular Moroccan town, wherein former lovers Rick (Humphrey Bogart) and Ilsa (Ingrid Bergman) unexpectedly meet again.
Why did it win? Because sometimes there's justice in the world, the stars align and choirs of angels encourage the voters to go for the right choice. And also because the competition wasn't exactly intense that year.
Did it deserve to win? Unequivocally, definitely, unarguably yes. Casablanca has a very strong claim to be the best film ever made - a script so good it'd make David Mamet weep with envy, perfectly pitched leading performances and an unspeakably good scene-stealing turn from Claude Raines (who gets all the best lines) - never mind the best one of the year. Aren't you glad it saw off the polished propaganda of In Which We Serve and the soppy piety of Song of Bernadette? It's a shame that Now, Voyager didn't get a nomination for Best Picture though - not that it should have beaten Casablanca, but it's the most notable omission, with Bambi close behind.
Worth a look? You have to ASK? Good god YES!