You're completely skipping over how funny this actually was. So Florence was actually using Catholic law to try and get Dante back, cause technically you're supposed to be buried at the church you were baptised in. So when a Medici, the ruling family of Florence, became pope Leo X he ordered Dante's bones to be returned. He slso ordered Michelangelo to build a mausoleum.
Anyway Ravenna couldn't refuse the pope and handed Dante's casket over to Florence. Another part of Catholic law is that opening someone's casket is desecration and a one way ticket straight to hell. So Florence was skeptical that Ravenna send them Dante and decided to do the unthinkable and opened his casket. It was empty, but Florence couldn't say so because if they called out Ravenna they'd have to admit to desecrating the corpse of their so called beloved poet. So they just pretended it didn't happen till Dante's bones were found behind a wall a couple hundred years later and again interned in a crypt in Ravenna.
Also a friend of Dante had his original grave in Ravenna inscribed with the text:
parvi Florentia mater amoris
Florence, mother of little love