What is the theme in The Everglades: River of Grass by Marjory Stoneman Douglas?

One of the dominant themes of the book during the period of the development of Florida is hostility. Hostility is the national reaction when one group of people tries to dominate another group. The Indians had inhabited the Everglades for centuries before the appearance of the white man. They would not easily give up their land or freedom and this was the source of continual conflict between the Indians and the white men. The white men, like Menendez, wanted to take control of the Indians and Florida but couldn't.