With new technological advancements there was no longer a need for as many workers and companies could now pay workers less due to the job being easier, in some countries such as England or the US this lead to revolts and rebellions, the likes of which paved the foundation of communism
Causes of the war 1812 included British attempt to restrict U.S trade, the Royal Navy's impressment of American seamen an America's desire to expand it's territory. The United States suffered many costly defeats at the hands of the British, Canadian and Native American troops over the course of the war. Including capture and burning of the nation's capital, Washington, D.C in August 1814. The war lasted 2years and 8months
you can find the rest of what your looking for on
https://www.history.com/topics/war-of-1812
In the 1800s they had 4 candidates running so thomas and burr had a tie so they decided no more than 2 candidates will run for president that's why they came up with the 12th amendment.