Frank Sinatra

Francis Albert "Frank" Sinatra (1915–1998) was an American singer and actor.

Beginning his musical career in the swing era with Harry James and Tommy Dorsey, Sinatra became a successful solo artist in the early to mid-1940s, being the idol of the "bobby soxers." His professional career had stalled by the 1950s, but it was reborn in 1954 after he won the Academy Award for Best Supporting Actor.

Frank Sinatra in Worldwar
Sam Yeager likened Ulhass and Ristin's reaction upon seeing Straha to a group of bobby-soxer's reaction to seeing Frank Sinatra.

Frank Sinatra in "News From the Front"
In the aftermath of the United States' entry into World War II, Variety reported that a New Jersey crooner was releasing a single entitled "Ain't Gonna Study War No More", with B-side called "Swing for Peace".

Literary Note
Turtledove does not specify that the singer is Sinatra, but the clues provided point at Sinatra.