Answer:
Muhammad's hegira from Mecca marks the beginning of a new polity. For the first time in Arabia members of a community were bound together not by the traditional ties of clan and tribe but by their shared belief in the one true God. Later believers, looking back on this event, recognized its seminal importance by designating it as the first year of their new era. In further recognition of this great event, the oasis of Yathrib came to be called Medina, "the city [of the Prophet]."
There were positive effects as well as negative effects.<span>
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The Battles of Lexington and Concord happened on April 19th of 1775. On that day British troops were sent to confiscate weapons and were attacked by American militia. The Battles of Lexington and Concord are famous for being “The Shot Heard Around The World” and the battle that started or “ignited” the American Revolutionary War.
The union was in the north where all of the factories were. The confederacy did not have the supplies that the union did.