The Civil War in the United States was primarily fueled by deep-seated economic, social, and political differences between the North and South. The expansion of territories through the Louisiana Purchase increased the demand for labor, leading to the proliferation of slavery.
With the Louisiana Purchase giving the United States more land, meant more plantations & more work to be done. So slaves were brought up. But States started banning the act of slavery but not all states wanted to ban slavery,. Causing an uproar, another key part of how the Civil War began.
State Versus Federal Rights
Nulification was a huge reason which was developed with the fight of state & federal. If they couldnt rule laws or acts unconstiutional then the would look to secession.
Economic differences between the north & south
With the invention of the Cotton Gin in 1793 by Eli Whitney meant the need for more cotton, bigger fields of cotton workers to pick the cotton, as the north became plentlyful of money the south was poor.
WWI
Subtopic
Alliances between countries before war. So if one was attacked their mutual agreement would mean their alli would join the fight.