Why was slavery so important to the south?

The south was abundant in Cotton that needed to be picked, which is extremely hard work, so Southerners would buy slaves to do the work for them, and any other type of hard labour, like cutting sugar cane,so if a southerner had a plantation and money, they would buy slaves to do this, this all came to an end with the civil War from 1861 to 1865 Thank goodness