The "wilde Heinz" (roughly translated as Good Times Harry or literally Wild Harry) of the title is Heinrich V, Duke of Brunswick (aka Heinrich der Jüngerer) while Eva von Trotha was his mistress for a considerable length of time. There's scandal, religious raillery and a faked death alongside ten kids involved, but strangely enough, not very well documented online.
The gist of the story was this: wilde Heinz was the duke of Brunswick who was married to the daughter of the count of Württemberg-Montbéliard when he took up the affair with Ms (von) Trotha. Heinz was also a Catholic who believed that the Lutherans were a plague that must be eradicated. Luther felt the same about him, and it was only the fortuitous deaths of Heinz and his eldest two arch-Catholic sons, (who died fighting at Sievershausen) and his failure to disinherit his third Lutheran leaning son, that stopped their portion of the Welf inheritance remaining Catholic.
Now what was all that about a faked death and scandal? Well Heinz wanted to cut his younger son out of the will (according to some sources, it had to do with Julius being more sympathetic to the reformers than his big brothers or old man). The scandal blew up about Heinz' relationship with Ms von Trotha (wikipedia's rather light on the details, and kings - or dukes in this case - had mistresses, so why this was any different I'm hoping to find out). Luther targetted her specifically, apparently. Not sure why Luther was targetting them, his protector the elector of Saxony kept a mistress and had had four bastards by her, and then there's the whole Philipp of Hesse debacle that I'm sure the reformers just shut their eyes and pretended it wasn't there.
So what does Heinz do? He decides to get his mistress away from the public eye. Not by any conventional means mind you, he FAKES her death. Supposedly, she died in childbed with their third kid. But it was a cover up, Heinz spirited her away to a remote castle and they had ANOTHER seven kids together. As if to stress the fact that his "beloved Eva" was dead, the duke went the whole hog, ordering candlelight vigils, requiem masses to be said, even putting the court in mourning (his namesake in England's got nothing on this guy, seriously).
Now that all this is out of the way, I'm looking for info on those ten kids, particularly birth years. These are pretty scarce since I can find birth years ranging from 1525 (when Eva was around 20yo) until 1548 (when she would've been around 43yo) despite something which was a pretty big deal in the day. So if there are any persons on the board who know more about this fascinating story, please share.