So how did the song happen? Well it came from the songwriting team of Sammy Fain, who wrote the music and Irving Kahle, who wrote the words.

Fain and Kayle had many hits together during their 17 year collaboration, dating back to 1925; including “I Can Dream, Can’t I?” and “Let A Smile Be Your Umbrella.”

They wrote “I’ll Be Seeing You” in 1938 for a Broadway musical comedy called “Right This Way.” But the show was a flop, lasting for only 15 performances. Sammy Fain once joked that a lot of theater-goers at those 15 shows, never even stuck around for the whole show. “Where’s the exit?”, Fain asked sarcastically. Well, Right This Way.

Then in 1943, the forgotten song was unexpectedly rescued from obscurity when someone must have realized the timeliness of its sentiment for the universal plight of wartime separations. Everyone big recorded it. Bing Crosby had one of the biggest hits with the song, as did Jo Stafford, Billie Holiday and Frank Sinatra.

But lyricist Kahle never knew of the song’s surprising late success. He had died the year before its resuscitation, at only 38, of a heart attack.

“I’ll Be Seeing You” differed from earlier Tin Pan Alley songs about loss and separation. It wasn’t about rejection by one’s beloved, about being dumped. It was a universal song about the power of love transcending time and distance.

And it wasn’t only lovers who related to the song. It was also meaningful to mothers separated from their sons and daughters; and to children separated from their parents.

In a World War II memoir, there’s the story of a young girl desperately missing her father. She writes, “the line ‘I’ll be looking at the moon, but I’ll be seeing you,’ had a profound effect on me. It was amazing to be able to look at the moon, and realize that all those miles away, he was able to look at the same moon.”

The song didn’t have that same salutary effect on everyone, however. Jazz critic Francis Davis spoke about that in an interview. “I grew up in a home where my mother had lost her brother in World War II,” Davis said. “We had my grandmother in the house as well. There were certain songs that we had to turn off when they came on the radio, because they just reminded my grandmother in particular, too much of her son. One of them was ‘I’ll Be Seeing You.’”

For soldiers during the war, the song was virtually ever present. One soldier recalls overhearing his buddy on the phone to his girlfriend. He was singing to her “I’ll Be Seeing You,” but he changed the words to “I’ll be squeezing you in all the old familiar places.”

But another soldier recalls hearing the song in the midst of the allied invasion of Sicily. “When we hit the beach,” he remembered, “we were all hit, the medics couldn’t get to us. I could hear a wounded soldier nearby singing ‘I’ll be seeing you.’ And then he stopped. I had listened to him die.”

Lyricist Irving Kahle had considered “I’ll Be Seeing You,” the greatest song he had ever written. And he’d often expressed his disappointment that it hadn’t become a hit – at least not during his lifetime. He would surely have appreciated knowing what his words came to represent, and what the song meant to so many millions of people, during very difficult times.

And all it took for the song to catch on was the complete catastrophic upending of the world order, in which parting became a normal fact of life for so many; and for which there just happened to be a song already made; a song that managed to distill the mood of an entire era.

At Kahle’s funeral, his longtime songwriting partner, Sammy Fain, arranged to have a special piece of music played during the service. Of course, that was “I’ll Be Seeing You.”

But our last words go to songwriter Sammy Kahn, who once said, “You know, old songwriters never really die, because their songs keep them alive, forever.