The Fieschi family was one of the major Genoese families. Of ancient origin, descendants of the Counts of Lavagna who had begun to enlarge their feuds within the Marca Obertenga in the eleventh century, the Fieschi were one of the four most important feudal noble families of the Republic of Genoa, Guelphs as they were Grimaldi, while Ghibellines were the Spinola and the D'Oria. Originating from the hinterland of Levante, they had their feudal center in the area of Val Fontanabuona. Here it was the center of their power; in fact the Basilica dei Fieschi was erected in Cogorno in the middle of the XIII century.
They were traditionally part Guelph, linked with a direct line to the papacy, so as to be able to confirm also two pontiffs coming from it, Innocent IV and Adriano V, famous antagonists of the Ghibelline-Imperial side of Frederick II of Swabia. Enriched with the merchandise, finance and land purchase, this family divided into numerous branches. The most important branch was the one called "di Torriglia"; this and that of "Savignone" descended from two brothers of Innocent IV and therefore they had been formed since the XIII century.
They always intervened in the internal issues of the city, as in the factional struggles, always on the Guelph side, even in the complex game of alliances, for example by connecting to the Ghibellines D'Oria through the marriage organized by Branca D'Oria between the latter's son , Bernabò, and Eleonora Fieschi or the even more ghibellini Duchi of Milan with the marriage between Luchino Visconti and Isabella Fieschi, concluded with the adventurous flight of his wife and the death of her husband. The Genoese bishop was usually linked to their family, whose building, the building that had once been the castle of Sarzano, dominated their minor houses around the present Vico Vegetti.
The Fieschi family fell into disgrace due to the failed conspiracy of Gian Luigi Fieschi "the Younger" (1547) against Andrea D'Oria, with whom he was also related through his wife. Gian Luigi "the Younger", head of the pro-French party, had rekindled the fight with the Spanish party, supported by D'Oria.
Presenting himself as a new Brutus, as an austere avenger of republican liberties against the tyrant's usurpations, after occupying the gates and the dock, he was about to take possession of a Doria galley when he suddenly slipped into the sea from a catwalk and drowned for the weight of the armor.
Giannettino D'Oria, nephew and designated heir of Andrea D'Oria, was also killed in the tumult, so that the fortunes of the uprising seemed favorable to the insurgents; instead the Fieschi, disorientated, gave themselves away. Since then the family lost much of the political importance in Genoa. At the Fieschi, persecuted hard, the assets were seized and many of them had to leave the city, taking refuge in France for the most part.
A first account of the Fieschi conspiracy was published in 1629 by the historian Agostino Mascardi (1591-1640): The conspiracy of Count Gio. Luigi de Fieschi del Mascardi inspired, in turn, the youthful work of Cardinal de Retz, La conspiracy of Count Gian Luigi Fieschi (original title La conjuration du comte de Fiesque), whose narration does not differ from Mascardi's text. For Cardinal de Retz, Gian Luigi Fieschi, "ambitious, daring and enterprising," plotted the conspiracy because, "passionately lover of glory, not having other opportunities to buy it, he did not think of the way to achieve it". Also for Friedrich Schiller, author of the tragedy The Fiesco conspiracy in Genoa (original title, Die Verschwörung des Fiesco zu Genua), Gian Luigi Fieschi was, as for Cardinal de Retz, an ambitious Plutarch hero; but in the tragedy of Schiller the story of the conspiracy was knowingly distorted: the conspiracy, aimed at restoring republican liberties in Genoa, succeeded in the drama of Schiller; but a perfect republican, seeing in Gian Luigi's ambition the prodromes of a new tyrannical regime, he killed him causing him to plunge into the sea with a push.