AbstractThis study examines Israel's failure to prevent Black October, the Hamas invasion that killed more than 1,100 people and sparked the Gaza war. The article synthesizes literatures of security and intelligence to advance three levels at which we must analyze Israel's missteps. The first is the intelligence level, where the state assessed threats. The second is operational, where officials devised military and security solutions, such as relying on technology to police the border with the Gaza Strip. The third level is political‐diplomatic, where the government pursued regional normalization agreements without focusing on solutions to the Palestinian file. Failures at all three levels were intertwined. The examination of these cascading mistakes opens a window into the interactions within and across these levels among military and civilian decision makers, and it suggests how they should be addressed going forward.