Alcatraz Island later invalidated the sale and paid Frémont nothing. Frémont and his heirs sued for compensation during protracted but unsuccessful legal battles that extended into the 1890s. Following the acquisition of California by the United States as a result of the Treaty of Guadalupe Hidalgo (1848) which ended the Mexican–American War, and the onset of the California Gold Rush the following year, the U.S. Army began studying the suitability of Alcatraz Island for the positioning of coastal batteries to protect the approaches to San Francisco Bay. In 1853, under the direction of Zealous B. Tower, the United States Army Corps of
Occupation of Alcatraz at 47 cents per acre, this amounted to $9.40 for the entire rocky island, or $5.64 for the twelve usable acres. Cottier also stated that the federal government would be allowed to maintain use of the Coast Guard lighthouse located on the island. The protesters left under threat that they would be charged with felony. This incident resulted in increased media attention for indigenous peoples' protests across the Bay Area. The United Council of the Bay Area Indian community initially considered writing a proposal and filing an application for the use of Alcatraz by Sioux people under the conditions of