In 1924, Busoni died. Weill started to work with the playwright Georg Kaiser who wrote plays in an Expressionistic style. Together they wrote an opera "Der Protagonist" (1926) which made Weill famous. The next year he worked with Bertolt Brecht. Together they wrote five songs which soon developed in a "Songspiel" under the title "Mahagonny". Between 1927 and 1929, Brecht and Weill wrote a new piece, an opera called "Aufstieg und Fall der Stadt Mahagonny" ("Rise and Fall of the City of Mahagonny"), in which five songs from the "Songspiel" were used again.