The concerto delle donne was a group of women who sang in the court of Alfonso II d'Este in the late 16th century in Ferrara. They took over the duties of a group of high-class amateurs. It seems that this older group was somewhat jealous of the newer group, but since both the duke and Luzzaschi liked the new group far better, there wasn't much they could do. Alfonso created the new group in part to amuse his child-bride, fifteen year old Margherita Gonzaga d'Este. Margherita's father was not very interested in women as singers, and when Alfonso tried to impress his father-in-law by parading the concerto for him, the old man stood up and said "Ladies are very impressive. In fact, I would rather be an ass than a lady", and then left. This makes it less surprising that when Alfonso convinced Margherita to get Laura Peverara from the Gonzaga court, he didn't have much trouble. Despite Guglielmo's dislike for the concerto delle donne, the Mantuan and Ferrarese courts were very close, frequently going on retreats together, and visiting each other.
With all this intercourse between the two courts, it's unsurprising that romance should follow. The handsome widow Tarquinia Molza fell in love with the composer/choirmaster of the Mantuan court, Giaches de Wert, and they subsequently had a very close relationship. In 1589 their affair came to light, and Molza was dismissed from the Este court, and immediately went to Mantua. Apparently the problem was less that Molza was having an affair, and more that Wert was seen as lower class than Molza, in fact that in his capacity as maestro di capella he was little more than a servant, and the relationship between them broke the social rules of the period because of this difference in class. This particular affair however ended far better than the imagined affair between Anna Guarini and a member of the armed forces. Although no evidence that an affair occurred comes down to us, La Guarina's husband Ercole Trotti apparently felt that he had enough evidence to convict her, and as she lay sick in bed killed her with a hatchet with the help of her own brother in 1598. The duke had tried to protect her, but he died in 1597.
In 1593 Carlo Gesualdo, noted composer, nobleman, and wife-murderer, came to the court with enough money, supplies, and people to happily stay for 3 years. The purpose of his visit was to marry Duke Alfonso's niece. We may well wonder what the duke thought of his niece marrying such a renowned murderer. It may be revealing to note that the duke, along with his "henchmen" had already murdered his sister Lucrezia's lover in 1579. This was apparently to maintain the prestige of the court, which is somewhat odd since many of his predecessors as dukes of Ferrara had been "natural" sons of previous dukes. Because of the tension caused both by this murder, and perhaps also the jealousy Lucrezia felt for her sister-in-law, Lucrezia started her own concerto delle donne, which met in the same palace as the original concerto.
Another member of the court was Giulio Cesare Brancaccio. Brancaccio had lived all over Italy, and had been part of the rise in the movement of virtuosic basses and the commedia dell'arte, and had also been a soldier. He considered himself a great cavalieri, and felt he would be a great addition to any court, even without his singing talents. Alfonso recruited him for the court in Ferrara in 1577, but seems to have had serious reservations. It's fairly clear that Alfonso only wanted him for his talents as a singer, and didn't want to have to listen to all of his deadly dull stories about the wars. Alfonso and Brancaccio frequently butted heads, and the final straw was when Alfonso asked Brancaccio to sing for the Duke de Joyeuse, and Brancaccio refused, resenting being ordered around like a common servant. The duke then dismissed Brancaccio. Brancaccio seems to have later repented of his bullheadedness, sending letters to the duke, and having friends intervene for him, including Giovanni Battista Guarini, but it was to no avail.
Margherita Gonzaga d'Este apparently was not sufficiently amused by the concerto, and so started her own project, which also utilized the talents of the members of the concerto delle donne. This was the balletto delle donne, which she may have had a lot of artistic control over. The members of the balletto frequently crossdressed, and one of their many performances was an adaptation of Orlando Furioso, an early feminist play.
Despite all the murder and affairs, a good time was had by all, and Alfonso proved that he had the most awesome crew in all of Italy. The Orsinis, Gonzagas, and Medici were all wicked jealous.