Duke Frederick Francis was the first member of the confederation to abandon Napoleon, to whose armies he had sent a contingent,[1] and in the following War of the Sixth Coalition he fought against the troops of the First French Empire —with the result that his new allies, Prussia and Russia, now offered his duchy to the Kingdom of Denmark.

At the 1815 Congress of Vienna, Frederick Francis joined the newly established German Confederation, and like his Strelitz cousin Charles II, was elevated to the title of "Grand Duke of Mecklenburg-Schwerin".

The Mecklenburg governance was still determined by the 1755 inheritance agreement (Landesgrundgesetzlicher Erbvergleich), which upheld the medieval hierarchy of the estates, which largely affected the social and economic development of both grand duchies.

In the subsequent reaction of the Mecklenburg nobility, backed by the Strelitz grand duke George, all the concessions which had been made to democracy were withdrawn and further restrictive measures were introduced in 1851 and 1852.

[1] In the dispute over neighbouring Duchy of Holstein which culminated in the 1866 Austro-Prussian War, Frederick Francis II supported the Kingdom of Prussia, whom he aided with Mecklenburg-Schwerin soldiers.

In the Franco-Prussian War (1870–1871), Prussia again received valuable assistance from Grand Duke Frederick Francis II, who was an ardent advocate of German unity and held a high command in her armies.

Thereby ended nearly eight centuries of continuous rule (only interrupted by Albrecht von Wallenstein from 1628 to 1630) by the originally Obotrite (West Slavic) Mecklenburg dynasty, beginning with their progenitor Prince Niklot (d. 1160).