Napoleon Augustus Jennings, writer, was born in Philadelphia, the son of a wealthy merchant, on January 11, 1856, and graduated from St. Paul's School in Concord, New Hampshire. He is best remembered for his autobiographical account of the career of Leander H. McNelly's Texas Ranger company in the Nueces Strip, A Texas Ranger, published in 1899. In 1874, at age eighteen, he moved to Texas, where after some adventures as a cowboy he joined McNelly's Special Force on May 26. George Durham, a McNelly ranger and author of Taming the Nueces Strip, claims that Jennings was not a regular member of the company but only a field clerk. Jennings remained with the company until February 1, 1877. When his father died in 1878 he returned to Philadelphia and attempted to run the family business, but was smothered by city life. He returned to the West in 1881 as a prospector, miner, stagecoach driver, and sign painter in Colorado.
After three years he returned to Philadelphia and began a career as a newspaper reporter. He served variously on the staffs of the Philadelphia News, Times, and Tribune and the New York Star and Sun. In 1892 he was back in Texas as a reporter for the San Antonio Express, but after five years he returned to New York for a long tenure with the Evening World. At the same time he was contributing copy on his days with the Texas Rangers to such magazines as Youth's Companion and the Saturday Evening Post, in which he published a biographical sketch of Jesse Lee Hall in 1900.
Jennings was married to operatic and vaudeville singer Edith Helena, and during the first decade of the twentieth century toured Europe and America as her manager and press agent. He covered the Mexican Revolution for the New York Herald. In 1899 he published his account of his adventures in Texas. The book is a fast-paced and highly readable narrative of fights with border raiders and the capture of such outlaws as John King Fisher and John Wesley Hardin. Walter Prescott Webb believed the book to be "of doubtful authenticity"; if the claims that Jennings made for himself were true, Webb stated, they "would make the exploits of Jack Hays and Ben McCulloch for the same length of time pale and insipid." Contrarily, J. Frank Dobie believed Jennings's book to be one of the best accounts of the Texas Rangers. Since 1899 the book has gone through seven editions, and John H. Jenkins III listed it among his "Basic Texas Books." Jennings died in New York on December 15, 1919.