Who is Bill Sewall and Wilmot Dow from The Rise of Theodore Roosevelt and what is their importance?

In his early adult years, Roosevelt frequently retreats to the backwoods of Maine for times of physical exertion, which prove helpful in calming his health. When he purchases Elkhorn, his second ranch, he employs his former Maine guides, Sewall and Dow, to manage the ranch. At first, they sense success, but failing markets and horrible weather eat up profits. After several years, Roosevelt sells out of the cattle business and Sewall and Dow leave the area.