The Military Gets The Island
The United States acquired California in the late 1840s, and then in 1850, President Millard Fillmore sent out an order saying that Alcatraz Island will get handed to the military. It made the island a military base, and they could use it for defense purposes.
John C. Fremont expected to receive a paycheck in exchange for the acquisition of his island. He thought it would be a simple transaction, but it looks like things got complicated. You can imagine how much stress he went through at that time. Losing any kind of estate would be so heartbreaking.