Who is July Johnson from Lonesome Dove and what is their importance?

At the age of twenty-four, July is the youngest of ten Johnson boys. He's worn the sheriff's badge in Fort Smith for two years, and in that time has grown into the job both in responsibility and understanding. A newlywed at the beginning of the story, his wife supposed to have been widowed and left with her young son, Joe, he has already taken the brunt of bad comments with a wife like Elmira who begins berating him just two days into their wedded bliss.