Why was there a war between the Union and the Confederates?

There were multiple causes of the American Civil War (1861-1865) fought between the Union and the Confederates. Key factors were Slavery, States' Rights and Socio-economic differences between the North and South, the most important factor was Slavery as it was prevalent in the other factors.

Slavery had become a divisive issue between the North and South as the South's was largely dependent on the production of products such as tobacco, cotton and rice. The North, on the other hand, had a mixed economy and had succeeded in urbanising. Therefore, the North relied on paid labour and leaned towards the abolition of slavery, the South, however, saw this movement as an attack on their way of life.

Alongside the slavery debate, the States' Rights debate also caused tension between the two sides. Southern States advocated for more self-governance allowing for states to make decisions for themselves instead of the federal government. This led to the concept of nullification which would allow states to ignore federal laws they deemed unconstitutional, most notably anti-slavery laws. This would later inspire the South to secede from the Union and form the Confederate States of America or the Confederacy.

Lastly, the North or the Union and the South or the Confederates were socio-economically different. As previously mentioned the North was industrialised with a growing immigrant population while the South was rural. Southern States were very proud of their lifestyle and felt that the Northern urbanite lifestyle was an attack on their Southern Way of Life. Especially surrounding the North's positive stance on import tariffs to further their industry which would directly affect the agricultural South as they relied on imported products from Great Britain and Europe in general. This led to any moral disagreement between the two becoming an economic one as well as Southern States felt that the government was favouring Northern industry over the South, despite industrialisation (mainly due to payment of labourers) being unable to compete with slave labour.