Concept of manifest destiny was based on expansionism.
Explanation:
Manifest destiny was started during 19th century in US by John O' Sullivan , he was a journalist by profession. The people believed that the country's main aim was to expand. The main idea behind Manifest destiny is to capture more land that will be beneficial for cultivation purpose mainly the people focused in cotton cultivation and this would spread slavery to these parts as well.
The effect was that it included expansion of westward portion of the United States as well as there was increase in tension regarding political interests between Northern and Southern parts.
Various drawback was there, they are as follows, There was increase in slavery, It is unconstitutional by nature, many people died as well as suffered specially Indians, war and conflicts took place.
I believe that one main reason why is 1. Woodrow Wilson (Who was a democrat) he believed that he did not need to bring anyone from the Senate, which was a Republican :) (I hope this helps! I read this from the internet, I was gonna post it to you but I dont know if its against the rules of Brainly :) If not let me know, and ill send the link)
The president is commander in chief and has the power to control the military. This allows him to enact martial law which can be used on our own soil to put down rebellions and threats to our public peace as well as our institution.
Basically my best bet is martial law.
They were conquered by the Spanish.
