Why was Columbus's "discovery" followed up by a concerted attempt to colonize and conquer the New World?
I beg to differ. There was, in fact NOT a concerted effort to colonize and conquer the New World; in fact it was originally considered little more than an obstacle in the path of a westerly path to the Orient.
The first people to frequent North and South America were the Spanish who were only interested in acquiring gold. Spain was at this point the poorest nation in Europe, and desperately in need of gold for its treasury; in fact it was gold, not spices, that Columbus promised to deliver from his expedition. Other European nations did not follow the Spanish in their gold search; rather they found it easier to attack Spanish shipments of gold bound for America. The first permanent settlement in the U.S., St. Augustine, Florida, was actually built as a fort to protect Spanish shipments from English privateers.
Almost all other explorers were attempting to find a Northwest passage to Asia. It was commonly believed at that time that major rivers traversed entire continents, thus rivers such as the Hudson River were believed to be passages across North America. Although there were some half hearted attempts at settlement, there was no serious attempt at colonization until the settlement of Jamestown in 1607, more than one hundred years after Columbus. Neither the Spanish nor French originally came to colonize. The Spanish came to exploit the area for gold; the French to trade for furs when beaverskins hats became popular in Euope. Only the British came with a serious intent to colonize.
The idea of an early "race to colonization" is a myth long perpetrated in elementary textbooks.
The main reason for this has to do with economics and power. When Columbus "discovered" the New World, it soon became clear that ownership of that new world would be beneficial to Spain. The resources found on the mainland helped Spain hold on as a major power. When other countries saw what colonization was doing for Spain, they wanted to have a piece of the action. For that reason, countries like France and Britain started to take their own colonies in the New World. They did not get gold and silver like the French did, but they did get colonies that provided them with wealth from things like tobacco, cotton, and coffee.