The Israeli military on Thursday released the first findings from its internal investigations into the colossal military and intelligence failure of Oct. 7, 2023, describing how senior officers vastly underestimated Hamas and then misinterpreted early warnings that a major attack was coming.

The inquiries attempted to answer the question that has confounded Israel since that day, when thousands of Hamas-led gunmen overran Israeli communities, army bases and a music festival: Where was the army?

Israeli military officials said they spent tens of thousands of hours probing the military’s intelligence-gathering and its subsequent response to the attack, in which about 1,200 people, mostly civilians, were killed and 250 taken hostage, in the deadliest day for Jews since the Holocaust. Survivors waited long hours to be rescued by soldiers after an attack that began in the early hours of a Jewish holiday.

Briefing reporters the day before publishing some of their initial findings, Israeli military officials, who could not be named under army rules, suggested that the failure stemmed from flawed assumptions about Hamas’s capabilities and intentions, as well as what some military officials have called an “addiction” to precise intelligence, which was lacking.

The mistaken view of Hamas had gone largely unchallenged within Israeli intelligence circles and senior command, and it led to a series of failures. Those included a chaotic military response in the first hours of the assault after troops deployed along the border were swiftly overwhelmed and the military’s Southern Command and Gaza Division was overrun.

The findings of military and intelligence failures largely match detailed investigations by local and international news media. But the military is now presenting its own version of the events for the sake of accountability, Israeli military officials said.