Because of Britain’s economic policy of mercantilism, the thirteen American colonies were

Mercantilism, an economic policy designed to increase a nation's wealth through exports, thrived in Great Britain between the 16th and 18th centuries. ... Because of this heavy reliance on its colonies, Great Britain imposed restrictions on how its colonies could spend their money or distribute assets.

i think it is a system for harvesting crops more easily

b) the confederacy had to pay all union war expenses.