In 1840 Hays was promoted to the rank of captain. He arranged for his men to be given colt revolvers. The Comancheswere used to fighting against men armed with single-shot guns and suffered heavy casualties at Plum Creek (1840), Enchanted Rock (1841) and at Bandera Pass (1842).
A fellow ranger, Nelson Lee, described Hays as "a slim, slight, smooth-faced boy, not over twenty years of age, and looking younger than he was in fact. In his manners he was unassuming in the extreme, a stripling of few words, whose quiet demeanor stretched quite to the verge of modesty. Nevertheless, it was this youngster whom the tall, huge-framed brawny-armed campaigners hailed unanimously as their chief and leader."
Hays was colonel in the 1st regiment, Texas Mounted Volunteers, during the Mexican War and took part in the battles at Monterrey and Mexico City.
In April 1849, Hays became Indian Agent for the Gila Apaches. He admitted finding it difficult to deal with people who had been responsible for killing his friends and resigned and on 3rd January, 1850.
Hays went to California during the Gold Rush and eventually was elected sheriff of San Francisco County and remained in office until 1853 when he was appointed surveyor-general of California. In this post he played an important role in the development of the city of Oakland.
In 1860 the Indian Wars broke out in Nevada. Hays was appointed commander of 549 volunteers and led his men to a successful victory at Truckee River.
After returning to Oakland he established a real estate business and over the next few years he became very wealthy. John Coffee Hays died in Alameda County, California, on 25th April, 1883.
At the time of my arrival in Texas, the country was in an unsettled state. For a long period of time a system of border warfare had existed between the citizens of Texas and Mexico, growing out of the declaration of independence on the part of the young republic. Marauding parties from beyond the Rio Grande kept the settlers of western Texas in a state of constant agitation and excitement. Besides these annoyances, the inhabitants of other sections were perpetually on the alert to defend themselves against those savage tribes which roamed over the vast region to the north, and which, not infrequently, stole down among the settlers, carrying away their property and putting them to death.
This condition of affairs necessarily resulted in bringing into existence the Texas Rangers, a military order as peculiar as it has become famous. The extensive frontier exposed to hostile inroads, together with the extremely sparse population of the country, rendered any other force of comparatively small avail. The qualifications necessary in a genuine Ranger were not, in many respects, such as are required in the ordinary soldier. Discipline, in the common acceptation of the term, was not regarded as absolutely essential. A fleet horse, an eye that could detect the trail, a power of endurance that defied fatigue, and the faculty of "looking through the double sights of his rifle with a steady arm," - these distinguished the Ranger, rather than any special knowledge of tactics. He was subjected to no "regulation uniform," though his usual habiliments were buckskin moccasins and overhauls, a roundabout and red shirt, a-cap manufactured by his own hands from the skin of the coon or wildcat, two or three revolvers and a bowie knife in his belt, and a short rifle on his arm. In this guise, and well mounted, should he measure eighty miles between the rising and setting sun, and then, gathering his blanket around him, lie down to rest upon the prairie grass with his saddle for a pillow, it would not, at all, occur to him he had performed an extraordinary day's labour.
There are few readers in this country, I venture to conjecture, whose ears have not become familiar with the name of Jack Hays. It is inseparably connected with the struggle of Texas for independence, and will live in the remembrance of mankind so long as the history of that struggle shall survive. In the imagination of most persons he undoubtedly figures as a rough, bold giant, bewhiskered like a brigand, and wielding the strength of Hercules. On the contrary, at the period of which I write, he was a slim, slight, smooth-faced boy, not over twenty years of age, and looking younger than he was in fact. In his manners he was unassuming in the extreme, a stripling of few words, whose quiet demeanor stretched quite to the verge of modesty. Nevertheless, it was this youngster whom the tall, huge-framed brawny-armed campaigners hailed unanimously as their chief and leader when they had assembled together in their uncouth garb on the grand plaza of Bexar. It was a compliment as well deserved as it was unselfishly bestowed, for young as he was, he had already exhibited abundant evidence that, though a lamb in peace, he was a lion in war; and few, indeed, were the settlers, from the coast to the mountains of the north, or from the Sabine to the Rio Grande, who had not listened in wonder to his daring, and gloried in his exploits.