The Spanish expedition that discovered the island took note that no humans seemed to populate it, despite just a short boat ride away from mainland California. For good reason: the treacherous, choppy currents could only be breached by large ships piloted by expert navigators. They named it “Alcatraz”, for the birds that seemed to dominate it, instead. In American hands, Alcatraz became a military fortress first, and a military prison later, starting during the Civil War. The discipline at the military prison was tough, but security was lenient. Prisoners could more or less freely move about the prison. The guards knew none could survive a swim through the rough, freezing waters.

On this day, October 12, in 1933, the military prison facility became a federal one, housing the most dangerous of the dangerous law offenders.

The civilian prison was designed with a much bigger focus on security than its military counterpart. Among the renovations to escape-proof the prison: new cell bars and window covers made of tool-proof steel. Utility tunnels were cemented in, and all prisoners were moved to the internal cell blocks, away from the prison walls. Meaning that even if a prisoner was to somehow dig themselves out of their cell (which happened on one occasion), they would still need to find a way to breach the outer wall of the prison.