In the musical powerhouse of Europe in the 15th century, one tune caught the imagination of the court composers.
This was The Armed Man (or in its original French L'Homme Arme").
A rousing first line warns that "the armed man must be feared" and goes on to tell everyone to arm themselves with a coat of mail.
The musician and broadcaster Rainer Hersch unpicks the facts we know of the tune and its words, making his way through 40 odd church masses by as many composers, who used the melody as a base.
Early music specialists Catherine Bott and Andrew Kirkman think the original song may have been a warning against the threat of the warring Turks, following the fall of Constantinople in 1453, but it could equally have been a popular children's or even a pub song.
Whatever its origin it became literally the "Smash Hit" of that time, but then, like much of pop music, it just went out of fashion and disappeared.
Rainer leaves the 15th century behind to find out why the song suddenly burst back into life in the 20th century.
Christopher Marshall heard it in his New Zealand school and composed a lively piece for wind band.
Karl Jenkins came across it during the Kosovo crisis 10 years ago, and composed his popular Mass for Peace.
This begins with the sounds of an approaching army, with the original tune bursting out at the climax.
The Master of the Queen's Music, Sir Peter Maxwell Davies, encountered it while studying in Italy, and composed a theatre piece where it becomes anything from a hymn to a foxtrot.
And this year the folk-group Mawkin:Causley released their first album and turned it into a fast-moving riff, which gets audiences on their feet.
Rainer traces the journey of the tune and the words, as it appears in these very different musical clothes.
The producers are Richard Bannerman and Merilyn Harris, and it is a Ladbroke production for BBC Radio 4.