Question: Louis Wilson Menk, was an American railway worker and executive, he served as the last president of Northern Pacific Railway 1966-1970, before the railroad was merged into which United States-based railroad company formed from a merger of four major U.S. railroads?
Sentence (from "John A. Haydon"): Haydon led the 1872 Yellowstone River expedition, where he faced a Sioux Indian skirmish led by Sitting Bull, Red Cloud and Crazy Horse at the Battle of Pryor's Creek, Montana.
Relevant evidence: No