Kaiser is a German title meaning emperor, derived from the Roman title of Caesar, as is the Slavic title of Czar.
The Holy Roman Emperors (962 - 1806) (the "First German Reich") called themselves Kaiser; they saw their rule as a continuation of that of the Roman Emperors and so used the name "Caesar" to reflect their supposed heritage. The rulers of the Austro-Hungarian Empire (1806 - 1918) also used the title Kaiser. In English usage, however, the title is mainly associated with the emperors of the unified German Empire (1871 - 1918) (the "Second Reich").
There were three Kaisers of the German Empire. All belonged to the Hohenzollern dynasty, which had ruled Prussia before ascending to the German imperial throne. The three Kaisers were:
The term German Empire commonly refers to Germany, from its consolidation as a unified nation-state on January 18, 1871, until the abdication of Kaiser (Emperor) Wilhelm II on November 9, 1918.
German colonial efforts from 1884 brought only a small overseas empire compared to those of Britain and France, although in the Herero Wars it shared the with those empires the phenomenon of armed conflict between natives and colonials.
Subsequent German foreign policy initiatives (notably the initiation of a large battle fleet under the naval laws of 1898 and 1900) drove Britain into diplomatic alignment (the Entente) with a Franco-Russian alliance already in the offing at the time of Bismarck's fall.
German history in the Middle Ages was strongly influenced by two opposing principles: universalism and individualism.
Charlemagne's German policy, therefore, was not a mere brute conquest, but a union which was to be strengthened by the ties of morality and culture to be created by the Christian religion.
Thus the emperors were by degrees so harassed in their family possessions that, towards the end of Rudolf's reign, the power fell into the hands of the nobility, and Matthias, though advised by his able minister Cardinal Klesl, was hardly able to maintain his authority.