Philippe le Hardi (Philip the Bold) inherits Burgundy on the 2nd of June 1364. The region is rich and possesses a lot of castles. But it suffers too from plague crises as in many parts in Europe since 1348, and war violences with England (since the defeat of Poitiers in 1356). In 1369 Philip the Bold marries Marguerite de Flandre (Margaret of Flanders), the richest heiress in Europe in the 14th c. In 1384 Philippe le Hardi inherits Artois and Flanders at the death of his father in law Louis de Male, earl of Flanders.
The name of Germolles appears in Burgundy archives in the middle of the 12th c. In 1300 the current château is called « fortified house of La Grange ». All along the 14th c., the domain of Germolles is expanding as well as the power of the name. Vassals are indeed paying obeisance to Guillaume II of Germolles. But in 1375 a spiral of loans is engaged. In five years, the debts are enormous and force to an always greater loss of the domain.
In 1380, Philip the Bold obtains Germolles by seizure. After all past troubles, the domain is in a very bad condition. Nevertheless Margaret of Flanders wants the place as is proved through the investments granted in the following years for its renovation and embellishing. The château of Germolles becomes one of the favourite residence of the ducal court until 1401 and will be even visited by Charles VI in 1389.
The renovation work lasted 10 years, between 1382 à 1392. In 1392 most of the main walls of the building are in place. The next step is the internal decoration. The master mason, Drouet de Dammartin, architect of king Charles V, the sculptors Jean de Marville and Claus Sluter, the painter Jean de Beaumetz participate to the work. Vineyards are cultivated around the residence, a fancy garden with a vast rosery and a kitchen garden are parcelled out and model and experimental sheep and cow-farming are organised.
The renovation work will stop only when Margaret of Flanders will go back to her private estates at the end of her life. After the death of the princess, the domain is not abandoned. It continues to be looked after and still hosts the ducal family but more episodically until 1430 when it becomes one of the few residences of the Dukes. The glory of Germolles appears and declines with Margaret of Flanders.