You have to remember that this movie freaking came out before Pearl Harbor.
Everything that Bogart did in the final act of the movie and all that he gave up was soaking in patriotism.
I saw this online when I did a search just now. I figured someone else would explain it better than I.
With the Fourth of July in sight and America therefore about to turn 243, the website www.streamingobservor.com has crunched some data to…
dhinckley.medium.com
"Okay, Rick isn’t technically fighting as an American. But really, he is.
Rick Blaine has been disillusioned by America, maybe even thrown out of America. He’s set up 3,700 miles away, well-off, well-liked, out of the line of fire. By the end of the movie it looks like he can even get the girl.
He renounces all that for the uncertain and often short life of a resistance fighter. The fact it’s the French resistance is irrelevant. By late 1942, Rick Blaine knows what the rest of the world knows: that America and free Europe are now a single team, embodying the hope and ideal, however flawed, of human freedom. It’s not coincidence that everyone who has enough money in Casablanca wants to use it to get to America.
Rick doesn’t have to join the fight, except he really does. No movie has made that simple definition of patriotism any clearer."