What did americans consider the most important benefit of the louisiana purchase?

This is debatable from source to source. One common answer is that it prevented the English from taking that terittory as war reparation cost from the French after winning and thus entering the Americas again as a power. Another common answer is that it doubled the size of the United States of America and provided the much needed land for people to settle.

South carolina was so angry about the election of lincoln that they seceded from the union on december 20, 1860. they attacked fort sumter later, on april 12, 1861.