The vast region of Lousiana had been under Spanish control for almost 20 years, it technically was the US western border and any expansionist idea passed through Lousiana, which eventually could have led to war.
The purchase, at a time when France and Spain were at war, ensured that Spain and France couldn't use the territory as leverage against the US or to use it as a base for any possible invasion. It also provided the US with full control of the Mississippi and gave the US access to the Gulf of Mexico.
He served from <span>March 4, 1933 – April 12, 1945. Three years is a term and he was President for 12 years, so he served 4 terms straight, the longest a president has ever done.</span>
