The fifth US President was James Monroe, who served from 1817 to 1825. He was the last president of the Founding Fathers and was a strong advocate for the expansion of the United States. During his presidency, he oversaw the acquisition of Florida from Spain and the Missouri Compromise, which allowed Missouri to enter the Union as a slave state. He also established the Monroe Doctrine, which declared that European powers should not interfere in the affairs of the Americas.