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
June 1962 Alcatraz escape attempt to death by guards because he wouldn't help investigators locate his brothers. A 2014 study of the ocean currents by scientists at Delft University and the research institute Deltares indicates that if the prisoners left Alcatraz at 11:30 pm on June 11, they could have made it to Horseshoe Bay just north of the Golden Gate Bridge, and that any debris that were released into the bay would have floated into the direction of Angel Island, consistent with where the paddle and belongings of the prisoners' was actually found. A 2015 History Channel documentary presented further circumstantial evidence gathered over