He made new sailing and navigating techniques, which made travel by boat much easier for the Europeans. But, on that note, his voyage to the new land forced Native Americans off of their land, and some of them into slavery. Columbus was violent and aggressive towards them in order to create what is now known as America.
Hope this helps a little bit
I believe the answer is smallpox, but I could be mistaken. There were lots of viruses threatening the population at the time but from what I know, smallpox was the largest threat.
<u>Non-Arabs were treated as second-class citizens regardless of whether or not they converted to Islam, and this discontent cutting across faiths and ethnicities ultimately led to the Umayyads' overthrow. The Abbasid family claimed to have descended from al-Abbas, an uncle of the Prophet.</u>
"form a more perfect union" Create a nation where states work together. ...
"establish justice" Make laws and courts that are fair. ...
"Ensure domestic tranquility" ...
"Provide for the common defense" ...
"Promote the general welfare" ...
"Secure the blessings of liberty"
The Industrial Revolution and the Agricultural Revolution (the latter caused the former)