Relations to Germanys immediate neighbors in 18th and 19th centuries

in the 1700's the Prussian empire occupied the territory in current Germany. Sweden was defeated by Russia, Saxony, Poland, Denmark–Norway, Hanover, and Prussia in the Great Northern War (1700–1721). This war ceased Swedish power in The Baltic Sea.
From 1740-1760 Prussia was at War with Austria and in 1748 Prussia gained the territory of Silesia. humiliated Austria formed and alliance with France and Russia while Prussia sought help from England. Defeating the Austrian army at the Battle of Burkersdorf and relying on British success against France, Prussia was finally able to force a status quo ante bellum on the continent. This result confirmed Prussia's major role within the German states and was established as a European great power. Frederick caused near-defeat of Prussia, and ruled as a much more peaceable ruler.

During the 1800's Napoleon had his war, at first Prussia was allied with France and invaded British territories. But as the war progressed Prussia had half its territories cut in 1807 with Napoleons first defeat. In the second Napoleanic war, Prussia was occupied but allied with france, with French defeat inevitable. Prussia sided with Russia and defeated the French in 1812.

Germany was finally unified in 1862, after the Franco-Prussian War.

source: https://en.wikipedia.org/wiki/Kingdom_of_Prussia