Elihu Root (1845-1937), a U.S. secretary of war and secretary of state and a senator from New York, was the most constructive conservative of his times.

Elihu Root was born at Clinton, N.Y., on Feb. 15, 1845. His father was a college professor of old New England stock. Elihu attended Hamilton College during the Civil War, graduating as valedictorian in 1864. After taking a law degree at New York University in 1867, he went into private practice in New York City. He married Clara Frances Wales in 1878; they had two daughters and a son and were a devoted family.

Root was a junior counsel to William Tweed during the notorious boss's trial in 1873. A decade later Root served briefly as U.S. attorney for the district of southern New York. An astute and resourceful legal counselor, he afterward became one of the nation's preeminent corporation lawyers. He advised the Havemeyer...