You'd have to be more specific about what time period. The country that is modern England has seen many wars over the centuries, and was not effectively united as a single country until the 10th century. The modern nation of Britain was the result of further unification in the 17th and 18th centuries, also after many wars.
King Alfred of Wessex is credited with the unification of England.
prussia
The Austro-Prussian War in 1866.
The unification of ItalyThe Franco-Prussian WarThe unification of Germany
Sucked his dick
The process of German unification began in the 18th century with the rise of Prussia as a dominant German power. However, the formal unification of Germany into a single nation-state occurred in 1871 following the Franco-Prussian War.
The first evident of the use of war paint was in Egypt. It was carved in a vase that described the war of the unification of northern and southern of Egypt. King Narmer lead the unification and the vase in which this historical even was recorded in was called the Narmer Palette.
If you meant which countries - That was the unification of Scotland with England and Wales.
Russia lost the war against the Ottoman Empire (modern day Turkey) when they allied with France and England. Because Russia was weakened, Italy and Germany had less of a threat from them and were able to unify 6 and 16 yrs after the war had ended.
The War of Liberation in 1813 and 1814 was a step toward German unification. The Revolution of 1848 was another step.
By making peace with the french
1. Second war of Schleswig 2. Austro-Prussian war 3. Franco-Prussian war