During World War One, numerous U.S. Navy ships were outfitted with new vacuum-tube radio transmitters, which were occasionally used to broadcast concerts to local installations, in this case from off the coast of California.
San Diego Evening Tribune, February 1, 1919, page 10:


    The radio department of Rockwell field promise a treat for music lovers tomorrow afternoon and evening which, so far as is known, has never been tried in the world before. The treat has been entitled "Moonlight Wireless Dance," the music to come from the battleship Marblehead and transmitted by wireless telephone.
    This affair has been arranged for the concession containing the cabaret and dance, and is in charge of Lieut. R. C. Roberts of the radio department. The apparatus will be tuned so as to sound as if the music is in the house, and not miles away.
    Arrangements have been made with the officer in charge of radio at Point Loma to cut down the spark there at regular intervals, in order to permit the use of the telephone for music without interference from outside sources. Although the apparatus can be tuned for one distance only, Lieut. Roberts expects to take no chances with the music being spoiled by heavy radio sparks.
    In a trial yesterday, a perfect reproduction was made of tones from the Victrola aboard the Marblehead, the volume of tone being greater than the musical instrument itself, and in hangar No. 4, this same entertainment will be found tomorrow, Lieut. Roberts promising an abundance of entertainment for all.