The forum thread where I found the dates is here: http://www.musiktreff.info/modules.php?name=Forums&file=viewtopic&p=44931 (posts #2 and 4). The link in the 4th post gives some more infomation: It says that it's difficult to find information about Gräfe, although his concerto belongs to the standard repertoire of every trombonist. It was the time of the "Karlsbader Beschlüsse", which the parliament in Frankfurt enacted in 1819 to suppress all liberal and national movements in Germany. The German Confederation ("Deutscher Bund") was the executive authority; every princedom from the old German Empire belonged to it, among them the duchy of Sachsen-Coburg-Gotha[, where Gräfe was a musician at court].