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
Alcatraz Island "Tony Hawk's Pro Skater 4" as a playable level, and in the video game "" in a downloadable zombie survival map called "Mob of the Dead". It is also featured as a playable racetrack in the 1996 arcade racing video game "". Alcatraz has also been portrayed often as a safe haven or base of operations in many post-apocalyptic movies, such as "The Book of Eli". Alcatraz even appears in "The Alchemyst" and "The Sorceress" by author "Michael Scott" and is depicted as a prison for the immortal "Perenelle Flamel". Alcatraz is featured in the episode "Bird Mummy of Alcatraz"