Short answers, pulled from the story.
The German Empire was founded on the 18th of January 1871 during a ceremony held inside the Hall of Mirrors at the Palace of Versailles. King Wilhelm I of Prussia accepted the crown of German Emperor while French troops besieged Paris outside the palace walls.
Chancellor Otto von Bismarck introduced old-age pensions, accident insurance, medical care, and unemployment protection for German workers starting in 1883. These programs became the largest social security systems in the world at that time and laid the foundation for the modern European welfare state.
The newly formed empire consisted of 25 distinct states including four kingdoms, six grand duchies, five duchies, seven principalities, three free cities, and one imperial territory. Prussia dominated this union by controlling two-thirds of both the population and the land area.
Herero and Nama tribes revolted against German colonists in 1904 after settlers seized their land for farming, ranching, and mining operations. General Lothar von Trotha dispatched troops to quell the uprising which resulted in the deaths of approximately 65,000 Herero people and 10,000 Nama individuals representing 80% of the total Herero population and 50% of the total Nama population respectively.
Kaiser Wilhelm II dismissed Chancellor Otto von Bismarck in March 1890 to pursue an aggressive foreign policy that abandoned Bismarck's complex alliance system. This decision led to Germany becoming isolated with only Austria-Hungary as a reliable ally and helped cause World War I through naval rivalry with Britain.
The German Empire ended on the 3rd of November 1918 when units of the German Navy in Kiel refused to set sail for a final large-scale operation. By the 9th of November Social Democrat Philipp Scheidemann proclaimed a republic from the Reichstag building leading to the abdication of Kaiser Wilhelm II and all German ruling kings dukes and princes.