What was a nations ultimate goal under mercantilism and how did great britain strive to achieve its goal?

The mercantile system believed the wealth of the world was a fixed amount, measured primarily in gold and silver accumulated.  The system promoted a nation selling its products abroad but not needing to buy from others, or imposing heavy tariffs if importing anything.  Colonies were created to provide raw materials and resources to the mother country and a market for the mother country's products.  Commerce was heavily controlled by the government through charters granted to specific trading companies.

Great Britain strove to achieve its mercantilism goal by using the American colonies as a way of enriching the British home government.  Britain also sought to control shipping by a dominant navy and merchant marine.

"Mercantilism" is a term we get from Scottish philosopher Adam Smith (1723-1790).  Smith criticized what he called the "mercantile system" because it restricted trade and thus restricted economic growth.   Smith countered by advocating a free market -- the opportunity for all nations to increase their wealth by exchanging goods freely with one another according to what would become known as capitalist principles.  

an economic reason that the south needed a reconstruction plan is that plantations, factories, and other businesses were destroyed during the war.