Answer;
Vikings accepting Christianity
Most important event during the period of European invasions is the vikings accepting Christianity.
Explanation;
At the beginning of the Viking Age, almost the entire population of Scandinavia was pagan, however the vikings had many Gods and it was not a big deal for them to accept the Christian god alongside their own.
The conversion of Vikings to Christianity occurred without violence, by the end of the Viking age most vikings had become fully Christian and were baptized and buried in that faith.
The first president of the United states was George Washington
The state that is governed by laws because the laws are the conditions of civil association
In the early days, Chicago was inhabited by Algonquian people. With the opening of the Illinois and Michigan Canal - that runs down to the Gulf of Mexico - and the first rail line to Chicago, the city started to become the national transportation hub with road, rail, water and, air connections. Also, Chicago sits in the center of the most fertile agricultural areas of the United States. Because of all those factors, Chicago grew quickly - in less than 20 years the population grew from 4 thousand inhabitants to 169 thousand.
D. Nestorian Christians condemned to be heretics