During the 18th century the War of the Austrian Succession and the Seven Years' War dealt heavy blows at the prosperity of the landgraviate, which was always loyal to the house of Austria.
At the close of the Seven Years' War (1763) France ceded to Great Britain all her territory east of the Mississippi except New Orleans, and Spain ceded Florida to Great Britain.
While the peace between the War of the Austrian Succession and the Seven Years' War lasted, Howe held commands at home and on the west coast of Africa.
In the latter year the Seven Years' War broke out, and Heyne was once more in a state of destitution.
A seven years' war followed, in which an English legion under Sir George de Lacy Evans and a naval force under Lord John Hay took part.
He was largely responsible for the Scandinavian Seven Years' War (1562-70), which did so much to exacerbate the relations between Denmark and Sweden.
Induced by political exigencies George allied himself with Frederick the Great when the Seven Years' War broke out in 1756; but in September 1757 his son William Augustus, duke of Cumberland, was compelled after his defeat at Hastenbeck to sign the convention of Klosterzeven and to abandon Hanover to the French.
On the approach of the Seven Years' War the island of Minorca was threatened by an attack from Toulon and was actually invaded in 1756.
During the stress of the Scandinavian Seven Years' War compelled him, in 1566, to recall the great financier, when his confiscated estates were restored to him and he was reinstated in all his offices and dignities.
Finding himself unable to resist the Muscovites, the grand master of the Order put himself under Polish protection, and this led to a seven years' war (1563-70) with Poland, during which the Swedes and Danes intervened on their own account.