Charlemagne forged a huge empire in mainland western and central Europe. In the decades after his death the empire split into 3 Kingdoms. The Western Kingdom would evolve to become modern France. The eastern kingdom would become the Kingdom of Germany. This would eventually become modern Germany and northern Italy. The middle Kingdom would break up fairly quickly, leaving Burgundy and later the Low countries and Switzerland as its legacy. France would emerge victorious over The English Crown and Burgundy at the end of the hundred years in 1453. From here on the German dominated Holy Roman Empire and France would be the two dominant powers in the territory of Charlemagne's empire.
The French Monarchs were much more successful however in centralising power and welding France into a cohesive cultural and political entity than were the German monarchs to their East. From a low point after the Battle of Agincourt, for four hundred years the French were successful in expanding France. Until the fall of Napoleon they were overall the leading military land power in Western Europe. They were the militaristic bully boys. The view that would later predominate for Prussia and Germany.
The tradition of the German King as protector of the Kingdom of Italy and the Latin Church resulted in the term Holy Roman Empire in the 12th century. In 1452 this was modified to The holy Roman empire of the German nation. Attempts by the Emperor to centralise this empire largely failed, at the time when the English, French, Spanish and Portuguese rulers succeeded in centralising their realms. In the early 16th century the German territories became demarcated from the territories that lay outside Germany. After 1279, the Habsburgs came to rule in the Duchy of Austria. Between 1438 and 1806, with few exceptions, the Habsburg Archduke of Austria was elected as Holy Roman Emperor. The Habsburgs ruled some of Germany directly.
It was the lack of centralised control that allowed the reformation to begin in Germany. The Reformation however left Germany further divided on religious grounds as well as being divided up into up to 1800 states. In 1525 the Dutchy of Prussia was born. In 1594 Brandenburg and Prussia were united through marriage. There was now another state controlling territories both and inside and outside the official borders of Germany. Protestant Prussia continued to grow and gradually became a a competitor to Austria for dominance in Germany. The partitions of Poland with Russia and Austria greatly increased the power of Prussia's position.
The final defeat of Napoleon in 1815, brought to an end the expansion of France. However the peace treaty concluded at the Congress of Vienna in June 1815 and the Treaty of London 19th April 1839 established a border between the French Latin states of France and the Germanic states of Germany and the Netherlands, that heavily favoured the French to the disadvantage of the Germanic people. There being no powerful unified Germanic state facing France for hundreds of years. The British encouraged the development of German nationalism as a counter to French expansionism during the Napoleonic Wars. And so the Congress of Vienna created the German Confederation, A loose association of 39 predominantly German-speaking sovereign states. A replacement for the defunct Holy Roman Empire, but again both Prussia and Austria had territory within and without the German borders.
German nationalist sentiment continued to grow, resulting in the brief creation of a Germany Empire in the revolutionary upheavals of 1848. This coincided with the outbreak of the 1st Schleswig War. The German National Assemby did not believe that all Austrian territory could be included in the German Empire. This led to the Crown being offer to Friedrich Wilhelm IV of Prussia who "refused the Crown from the gutter" and forced the Frankfurt National Assembly to disband in December 1849.