William Howard Taft was born in Cincinnati, Ohio, on September 15, 1857. He graduated with very good grades and later attended Yale and the University of Cincinnati Law School. Taft began working as a courthouse reporter and passed the Ohio bar exam in 1880. His father, a Republican who also served on Cincinnati's City Council, had run for Ohio governor in 1875, but lost. In 1890, President Harrison selected the younger Taft to be Solicitor General of the United States at the age of 32. Between 1896 and 1900, Taft served as a judge of the United States Sixth Circuit Court of Appeals and as a professor of constitutional law at the University of Cincinnati.

Taft later became the Governor-General of the Philippines, a territory that the United States had acquired from Spain following the Treaty of Paris in 1898. At that time, there were more than 70,000 U.S. troops involved in an effort to resist a major nationalist insurgency in the Philippines, and Taft drafted a Constitution for the territory, largely modeled after the U.S. Constitution. In 1904, Roosevelt appointed Taft as his Secretary of War and immediately sent him to Panama, where the canal was already under construction.

The Panama project was not going well in 1904, but Taft ultimately helped to complete one of the most difficult engineering jobs in the history of the world. Taft was next sent to Cuba, where he served as Provisional Governor.

Shortly before the Treaty of Portsmouth conference, Taft traveled as War Secretary to Japan and signed a memorandum guaranteeing that the United States would not interfere with Japanese control of Korea as long as Japan would not invade the Philippines. Although Taft had risen to the very highest level in the Roosevelt administration, he found that resolving political disagreements caused him great anxiety, and he decided not to run for president. It turned out that Teddy Roosevelt had big plans for Taft, however.