Beethoven's brother Carl married Johanna Reiss on 25 May 1806, prompting Ludwig to write many years later, 'My brother's marriage was as much an indication of his immorality as of his folly'.
Johanna was the daughter of a prosperous Viennese upholsterer; her mother was the daughter of a wine merchant and local mayor in lower Austria. As a dowry her father gave her the not inconsiderable sum of 2,000 florins, and she was to inherit a large house in the Alservorstadt suburb.
Beethoven's objection to his brother's marriage was based more on Johanna's reputation than her means. She was, it appears, generous with her favours before her marriage - and it is probable this did not change after she became Carl's wife. It is said she gave birth within months of Carl's death, and given his illness it is unlikely he was the father. She became pregnant again in the spring of 1820 - nearly five years after Carl's death - by a finance councillor named Johann Hofbauer.
Beethoven was appalled by Johanna's immorality and frequently ran her down both in conversation and letters; he nicknamed her "Queen of the Night", after the character in the Mozart opera The Magic Flute. He used her reputation - as well as her conviction for stealing money from her husband (cf. Carl van Beethoven) - against her in the long legal process over custody of her son, Karl.
The court battle lasted for nearly five years, beginning within two weeks of Carl's death. Beethoven won the first round. Three years later Johanna appealed on the grounds that Karl had run away from his uncle to be with her. She won, after the upper court established that Beethoven was van and not von - and therefore not a member of the nobility - and handed the case down to the lower court.
In early 1820 Beethoven petitioned the Court of Appeal, probably again citing Johanna's immorality, which was confirmed by her illegitimate pregnancy. This time he won.
Johanna made one last desperate attempt to win back custody of her son by appealing directly to the Emperor. He refused to intervene.
When, in 1826, Karl attempted suicide, it was to his mother's house that he was taken, superficially injured - probably at his own request. There is some evidence that in his final years Beethoven softened his relationship towards Johanna.
Johanna suffered greatly at Beethoven's hands. It is hard to understand what drove him to drag her through the courts for so many years in order to gain custody of her son. (She was not the only one to suffer; Beethoven's own creativity and health were drastically affected.)
Maynard Solomon suggests he secretly desired her and his aggression towards her can be seen as a denial of this - though he accepts rumours that Beethoven was in love with her were put about by Johanna herself, causing Beeethoven to write in a letter: '... And yet what talk we had to listen to about fine clothes, of which Frau B[eethoven] has accused me, and on a former occasion the statements that I was supposed to be in love with Frau B[eethoven] and so forth. Is that kind of talk suitable for a Guardian or, to put it more plainly, do those people indulge in that kind of tittle-tattle?'
I have been unable to find any contemporary image of Johanna van Beethoven, or indeed any physical description of her. She outlived Beethoven by 41 years and her son Karl by 10 years, dying in her eighties.
As far as I have been able to establish, she never wrote or said a single word against her brother-in-law in the years after his death.