When they were children, Wolfgang and Maria Anna “Nannerl” Mozart (1751-1829) were a successful duo, a pair of enfants prodiges who shared exhilarating experiences, such as performing for the kings of Europe, and dramatic ones, such as illnesses that took both of them to the brink of death. In 1765, in The Hague, Nannerl became ill first with bronchial catarrh and then typhus fever, and her condition soon became so grave that Last Rites were administered. When she miraculously recovered, her father Leopold ordered six masses to be said in thanks. Some time later, Wolfgang also recovered from a severe illness but in his case there were nine masses! In this different treatment one can perhaps detect the germ of the conflicts between brother and sister that came out later on.

During their childhood and youth, however, their relationship was very close. From their collection of letters one senses an affection and interest in the good health, thoughts and state of mind of the other; at least in his letters because, unfortunately, hers have been lost for the most part — just as her diary has come down to us in a state of some mutilation. Wolfgang readily directed affectionate and farcical expressions to her, as in this postscript to a letter of his father’s written from Milan on 17 February 1770 — in which he calls her “Mariandel” (another name of endearment for Maria Anna):
Here I am, all yours, Mariandel, and I’m arse over tit with happiness that you had such a dreadfully fine time… a hundred kisses to you, big and small, on that marvellous horseface of yours.
Sometimes he lavishes high-sounding praise, as in a letter from Vienna of 14 August 1773:
I hope, oh my queen, that you are enjoying the best of health and that from time to time, or rather every so often, or better now and then or even better “qualche volta”, as the Italians say, you would like to offer up one or your momentous and most excellent thoughts, that at every moment drop from that most fine and weighty of intellects, that you possess hand in hand with beauty, and although almost none of the above could be claimed by one of such tender years and a woman, you, oh queen, possess it all in such measure as to confound every man, even including the old ones. Good-bye. (Now that’s what I call serious!)
Occasionally, on the other hand, Wolfgang took the liberty of teasing Nannerl about her love life. She had some admirers that it seems she left languishing. This he wrote to her from Milan on 26 January 1770:
I rejoice with all my heart that you had fun sleighing and I wish you a thousand other occasions for enjoyment, so that you have a happy life. There was just one thing: that you made Herr von Mölk long for you and pine away and then didn’t go in the sleigh with him, afraid that he might make you capsize. How many handkerchiefs must he have soaked that day, crying over you! He must surely have taken an ounce of tartar beforehand, to purge the filth that infests his body.
Incidentally, poor Joseph von Mölk (1756-1827), the suitor so ruthlessly turned down by Nannerl, later became a priest.
With the passing of the years, the teasing tone disappears from Mozart’s letters and instead a certain nostalgia for their childhood’s affectionate complicity s shows through. On 20 July 1778, Wolfgang writes to his sister from Paris excusing himself for being late in sending her wishes for her name day:
I know that, like me, you don’t appreciate high-sounding words and you can be sure that with all my heart I wish you every happiness, not just today, but every day, and that I wish it sincerely, as sincerely as a brother who wants the best for his sister can. I’m sorry that I haven’t been able to write a piece of music in your honour, as I did some years ago. Also, I hope that the happy time has not passed when brother and sister, once so united and devoted, can tell each other what they have on their mind and in their heart. Goodbye for now, keep well, and love me as I love you. I embrace you with all my heart and with all my mind and I am ever your sincere and loyal brother.
The piece of music to which Mozart refers is Divertimento “Nannerl Septett” KV 251, that he had written for Nannerl’s name day in 1776.
These declarations of tenderness were repeated many times. Wolfgang took care to reassure his sister that physical distance had not even slightly weakened his affection for her, and he was concerned about her health. What’s more, the more he freed himself from his original family to find his own autonomous road in life, the more he exhorted her to do the same. Years later, he went as far as begging her to follow his example by escaping the overwhelming control of their father, Leopold Mozart, and move to Vienna with her innamorato, Franz Armand d’Ippold. He wrote a moving letter to her from the capital on 19 September 1781:
Believe me, dearest sister, I am extremely serious when I say that the best cure for you would be a husband, and with all my heart I would wish you to be married soon. […] There are very few opportunities for you and d’Ippold in Salzburg; or rather, I would say none. But couldn’t d’Ippold find something here? I imagine that he is not completely without means. Ask him, and if he thinks the idea is at all feasible. He only has to tell me what I can do to help him […]. If it works, you could certainly get married; in fact, believe me, you too could earn a fair amount here in Vienna, for example playing in private concerts and giving lessons. You would be in demand and well paid.
Unfortunately, just as she did not follow her brother’s advice and dedicate herself to composition (as reported in this article), neither did Nannerl listen to him in this case. She did not marry d’Ippold — who it seems Leopold Mozart did not like, precisely because his position was not sound enough — and she did not move away from Salzburg. In 1784, at 33 years of age, she finally married: a wealthy man, Baron Johann Baptist von Berchtold zu Sonnenburg, twice a widower and father of five. It is quite probable that it was merely a marriage of convenience. Nannerl moved into the Baron’s home in Sankt Gilgen and gave up all musical activity to take care of the family.
There are no signs of a particular event that provoked a break in the relationship between brother and sister, but a break there definitely was. Perhaps it was simply a matter of lack of understanding and agreement between two different characters, accentuated over the years and coming to the fore in their respective, contrasting choices in life. Unlike Wolfgang, Nannerl was never able to put her own interests before those of her family, or openly to oppose her father and this created inevitable resentment and conflict.
Somehow she never managed to free herself from the role of daughter, perhaps because her gilded childhood of European tournées was the happiest time in her life and a refusal to become psychologically autonomous was a way of making it continue. It was also an attempt to vindicate herself from the evident preference that her father always held for the male child. Furthermore, both d’Ippold and Baron Berchtold zu Sonnenburg were much older than her and could have been father figures.

What is more, Leopold Mozart, a man who cleverly kept control of the family by emotional blackmail, did not hesitate to set his children against one another for his own ends. When Wolfgang did something that he didn’t particularly like, he wrote to him saying that his thoughtless behaviour was making his sister suffer horribly. For example, in 1778, the young Mozart was travelling towards Paris with his mother, just as his father had carefully arranged, when he met a family of musicians, the Webers. He decided to change plans, go to Italy with them and send his mother home. On 12 February, Leopold wrote him a long letter (one of the most famous of the entire Mozartian correspondence) in which basically he wheeled out the good old words: “How can you treat me so badly, after all I’ve done for you?” And he wrote as a postscript that Nannerl had cried for two whole days. Do we really believe that?
In any case, the result of all this was that neither of the two siblings attended the other’s wedding, and neither got to know the other’s children (Nannerl only met Franz Xaver Wolfgang Mozart, the Maestro’s younger son, many years after his death). And when their father died in 1787, Nannerl did not personally inform Wolfgang; in fact, she didn’t even tell him that he was ill.
Then the disagreement became explicit and expressed itself in the not unusual form of arguments over the legacy. Wolfgang wrote that he could not possibly leave Vienna (because he was working on Don Giovanni) and he asked her to send him an accurate copy of the will, not wanting to forgo reading it (because, probably, he didn’t trust her). He also stated that he was in agreement with the idea that his sister should sell the most valuable objects by auction. However, Nannerl told him that he could forget about his share of the proceeds of the auction. On 16 June he wrote her just a few, dry lines:
As I have told you a thousand times, if you were without a home I would leave you everything with great pleasure. But as you now have no material needs, so to speak, while I have precise necessities, I consider it my duty to think of my wife and son.
Hence a negotiation began between Mozart and his brother-in-law, at the end of which the assets were more or less equally divided. However, Nannerl kept many things of value for herself, among which were some musical instruments and the jewels that had been given as gifts during the European tours when they were children. She was also very disinclined to give the scores of his compositions back to her brother.
From then onwards, contact by letter was ever colder and more rare and in the last three years of Mozart’s life they ceased completely. However, following the unexpected death of her brother, Nannerl found a possible redemption from the breakdown of their relationship by actively collaborating with his biographers and with the publishers of his immortal music, thus contributing to the creation of the myth.