The city history of Fresnay-sur-Sarthe really begins with the erection of the castle, which was initiated approximately in the 10th century (perhaps in the 9th century), under the reign of Charles the Bald. The purpose of the castle was mostly to ensure protection of the river crossing.
William the Conqueror captured the castle twice; first in 1063, then again in 1073. Young Robert of Bellême, who particularly distinguished himself during the siege, was proclaimed as a knight from William's hand.
The strategic importance of the Castle of Fresnay was particularly highlighted during the Hundred Years' War. Successively occupied by the adventurers of Philippe de la Chèze, in 1356, then captured by the English troops of King Henry V, in 1417, it came back to the French, thanks to Ambroise de Loré, future companion of Joan of Arc; Captain of the Castle in 1418, he later became 'Prévôt' de Paris.
In 1420, the city was again taken by the English who occupied the place for thirty years (1420 to 1450). Heavily affected by the Hundred Years' War, Fresnay also had to suffer from the Wars of Religion; in 1562, it was devastated by the Huguenots. From then, the castle started to gradually fall into ruins.
By the late-17th century all that was left of the castle was its gate house, a salt house, the bases of the curtain walls and a ruined keep. It was then donated by Louis XIV of France to the town to serve as a prison and court.
At present the grounds of Fresnay-sur-Sarthe Castle are a nice public park and it is freely accessible. The salt house is now a small local museum.
Ehrenbreitstein Fortress was built as the backbone of the regional fortification system, Festung Koblenz, by Prussia between 1817 and 1832 and guarded the middle Rhine region, an area that had been invaded by French troops repeatedly before. The fortress was never attacked.
Early fortifications at the site can be dated back to about 1000 BC. At about AD 1000 Ehrenbert erected a castle. The Archbishops of Trier expanded it with a supporting castle Burg Helferstein and guarded the Holy Tunic in it from 1657 to 1794. Successive Archbishops used the castle's strategic importance to barter between contending powers; thus in 1672 at the outset of war between France and Germany the Archbishop refused requests both from the envoys of Louis XIV and from Brandenburg's Ambassador, Christoph Caspar von Blumenthal, to permit the passage of troops across the Rhine.