To write any book is an adventure, but to write this book has been the kind of gay and romantic experience that makes any man who has partaken of it a debtor forever to the Giver of Delights. Historical research, contrary to popular opinion, is one of the most thrilling of occupations, but I question whether any biographer has ever had a better time gathering his material than I have had. Amid the old scenes, the old epic life of the frontier has been re-created for me by the men who were the leading actors in it. But my contact with it has not been only vicarious. In the course of this most grateful of labors I have myself come to know something of the life that Roosevelt knew thirty-five years ago--the hot desolation of noon in the scarred butte country; the magic of dawn and dusk when the long shadows crept across the coulees and woke them to unexpected beauty; the solitude of the prairies, that have the vastness without the malignancy of the sea. I have come to know the thrill and the dust and the cattle-odors of the round-up; the warm companionship of the ranchman's dinner-table; such profanity as I never expect to hear again; singing and yarns and hints of the tragedy of prairie women; and, at the height of a barbecue, the appalling intrusion of death. I have felt in all its potency the spell which the "short-grass country" cast over Theodore Roosevelt; and I cannot hear the word Dakota without feeling a stirring in my blood. It was Mr. Roosevelt himself who gave me the impulse to write this book, and it was the letters of introduction which he wrote early in 1918 which made it possible for me to secure the friendly interest of the men who knew most about his life on the ranch and the range. "If you want to know what I was like when I had bark on," he said, "you ought to talk to Bill Sewall and Merrifield and Sylvane Ferris and his brother Joe." I was writing a book about him for boys at the time, and again and again he said, "I want you to go out to Dakota!" On one occasion I referred to his life in the Bad Lands as "a kind of idyl." "That's it!" he exclaimed. "That's it! That's exactly what it was!"