Henry Lewis Stimson was born on September 21, 1867, into a wealthy New York City family. His mother died when Stimson was eight years old; his father was a Civil War veteran who established himself as a stock exchange speculator, then as a prominent surgeon. Stimson graduated from Yale University in 1888 and Harvard Law School in 1891. He married Mabel Wellington White on July 6, 1893.

In 1891, Stimson entered the law firm of Root and Clarke. Elihu Root (1845- 1937) was a leading New York lawyer who in 1899 would become secretary of war. Stimson and another lawyer started their own successful law firm in 1899. In 1906, President Theodore Roosevelt appointed Stimson the U.S. attorney for the Southern District of New York. Stimson built a staff of excellent young lawyers that included Felix Frankfurter (1882- 1965), a future Supreme Court justice. His office won a series of cases against companies that were...