The Civil War was the most catastrophic event in American History. More than 600,000 people were killed in the war, which was greater than all those who had died in all other American wars combined. It brought unity between the north and the south, and had far-reaching effects on the direction the young nation was taking. The south was placed under military rule and was divide into military districts, reconstruction, the plan to rebuild America, began, and industrialism began as a result of the increase in wartime production and the development of new technologies. The greatest impact of the Civil War, however, was that slavery had been effectively abolished, although not official until the 13th amendment. The first African Americans that arrived in Jamestown in 1619 were neither slaves nor free. They were indentured servants who became free when their time was complete, usually ranging from 5, 7, or 10 years. This was short lived and slavery gradually replaced indentured servitude as primary means for plantation labor in the South. Virginia was the first British colony to legally establish slavery in 1661, followed by Maryland and the Carolinas, Georgia was the only Southern colony that fought against slavery, until seventeen years after its formation, and it too accepted it. Northern colonies also had its slaves, but the basis of its economy did not promote the need for them, unlike the South, which focused primarily on agriculture and managing plantations. Because of this, the slave population in the North remained small, and the slaves were frequently granted their freedom.