Who is Captain Woodrow F. Call from Lonesome Dove and what is their importance?

A hard task master, Captain Call is not one to sit idle for long. He is used to putting in a hard day's work, and expects the same from any man in his employ. He tires of being the Captain though. He was fine when the Indians roamed the land, and led the men into many a skirmish, but now all that business had been quiet for many years, and he wishes that someone else would take the lead now and then instead of always looking to him for answers to everything. He is a stubborn man, and once he decides on something, it is almost impossible to change his mind. Hell Bitch, his new horse, is a prime example.