Most popular song during World War 2?

The most popular song during World War 2 was "White Christmas" by Bing Crosby. It was released in 1942 and became an instant hit, selling over 50 million copies worldwide. The song was also featured in the 1942 film of the same name, which starred Crosby and Danny Kaye. "White Christmas" has been covered by many other artists, including Elvis Presley, Frank Sinatra, and Michael Bublé.