In the war's final days, the U.S. Embassy in Saigon used the song to signal evacuation for Vietnamese who had cooperated with American forces.
The code for evacuation, broadcast across South Vietnam on American Forces Radio, was "THE TEMPERATURE IN SAIGON IS 112 DEGREES AND RISING. THIS WILL BE FOLLOWED BY THE PLAYING OF 'I'M DREAMING OF A WHITE CHRISTMAS'."
The advisory for the clandestine op, "Operation Frequent Wind", was in the American Embassy's 15-page booklet "SAFE" ("Standard Instruction and Advice to Civilians in an Emergency").
An insert page read, "Note evacuational (sic) signal. Do not disclose to other personnel. When the evacuation is ordered, the code will be read out on American Forces Radio" after playing "White Christmas".
"SAFE" included maps of Saigon pinpointing "assembly areas where a helicopter will pick you up."
"Operation Frequent Wind", the largest helicopter evacuation in history April 29-30, 1975, and its naval rescue operation, saved some 77,000 Vietnamese who had cooperated with American forces, according to "The Timeline of the Vietnam War" by Kevin Dougherty and Jason Stewart (Thunder Bay Press).
On April 30, North Vietnamese forces entered Saigon and took over South Vietnam, ending the war.
I learned about that signal when I visited Vietnam on the 30th anniversary of its fall. My guide Tano said that his uncle, who had worked closely with U.S. forces, heard the song signal but "got trapped in the desperate chaos of those final hours in Saigon, and missed the last airlift." His uncle was sentenced to many years in Communist "re-education" camps.
Tano's Catholic priest, who had supported U.S. troops, was executed.
"White Christmas" and the United States could not help save him or tens of thousands of other South Vietnamese in that frantic frequent wind. Then-President Gerald Ford termed April 1975 "the cruelest month".
That first Christmas of World War Two, American GIs adopted the song as a patriotic somewhat secular anthem. Six decades later, it would play an ironic role in a very different war.
The song has become the world's top-selling song, more than 50 million copies, according to the Guinness World Records, and the most recorded tune. Its 500 or so versions are by Elvis, Alvin and the Chipmunks, Bob Marley, The Drifters, the Three Tenors...
In "White Christmas: The Story of an American Song" (Simon and Schuster), author Jody Rosen comments that Irving (Izzy) Berlin, born Israel Beilin a cantor's son, envisioned the song as a mere "throwaway" novelty number. But eventually, he termed it "'the best song anybody ever wrote.'"
May your days be merry and bright, and may we have peace on earth.