Karl van Beethoven, son of Carl and Johanna, was the only child of the three Beethoven brothers, and thus the sole Beethoven of the next generation.
Beethoven, his uncle, saw Karl as the Beethoven to carry the illustrious musical name forward. Even before Carl's death, Beethoven saw himself as guardian of his nephew, determined to rescue him from the clutches of his (as he saw it) immoral mother.
The protracted legal action that Beethoven waged against his sister-in-law is testament to his overriding determination to be in sole control of Karl's destiny.
In time he came to see himself as Karl's father, and pleaded with the boy to accept that.
Karl, naturally, was confused emotionally. The legal action took place while he was aged between ten and 14. He had the strain of that - at one hearing having to stand up in court and give evidence - as well as coping with the death of his father and the obvious distress of his mother.
Beethoven - after winning custody of Karl -- forbade him to see his mother. The boy frequently disobeyed him, running away to be with her. On one occasion Beethoven called the police to have him forcibly returned.
Beethoven placed Karl in a series of schools, most notably Giannatasio del Rio's and Joseph Blöchlinger's. Determined that Karl should become a musician, Beethoven ordered his pupil Carl Czerny to give him lessons. Beethoven refused to listen when Czerny told him the boy had no musical talent.
Karl lived unhappily with his uncle for a time before becoming a student of philology at the University of Vienna in 1824. Shortly after, he informed his uncle of his intention to pursue a military career - which sent Beethoven into paroxysms of rage.
In July 1826, in a state of supreme emotional turmoil, Karl buys a pistol with the intention of committing suicide. His landlord finds out and alerts Beethoven.
On 29 July Karl pawns his watch and buys another pistol. With both pistols and a supply of gunpowder he climbs to the Rauhenstein ruins in Baden - where he had so often climbed with his uncle - loads both guns and puts the first to his head. He misses. With the other he grazes his temple.
When he is found, he asks to be taken to his mother's house. The combination of the attempted suicide and Karl's return to his mother devastates Beethoven. It is fair to say he never truly recovers from the shock. It is final proof he has failed in his attempt to be father to Karl.
In August Karl is admitted to hospital where - as a potential suicide - he is forced to undergo religious instruction.
In September Beethoven takes Karl to stay with Johann and Therese at Gneixendorf for a fraught stay that lasts until the two brothers fall out irreconcilably and Beethoven leaves with Karl for Vienna on 1 December.
One month later, on 2 January, Karl leaves for military service in Iglau in Bohemia, his hair combed forward to hide the scar of the bullet wound. He says goodbye to his uncle in an unemotional meeting - though he certainly knows Beethoven is mortally ill.
It turns out to be the last time he sees him. He fails to return to Vienna before Beethoven's death on 26 March 1827, though he takes part in the funeral three days later.
Karl van Beethoven left the army in 1832, marrying Caroline Naske in the same year. They had four daughters and a son, whom they named Ludwig. Karl briefly tried his hand at managing property, but was able to live comfortably as a private citizen on his inheritance from his uncles. He died at the age of 52 from liver disease. His wife outlived him by 33 years.
Their only son emigrated to America, where he worked for the Michigan Central Railroad Company of Detroit. He married a concert pianist, Maria Nitsche. Their only son Karl Julius died childless, and thus the Beethoven name died out.
The only contemporary image of Karl van Beethoven - an unsigned miniature portrait - shows him in military uniform, his hair combed forward to hide the gunshot wound. He has a sensitive, almost feminine face, with large dark eyes and full lips.