The assessment contradicts a Republican charge that U.S. armed forces were ordered to stand down while Ambassador Chris Stevens and three other Americans were killed.
Two of those killed in the Sept. 11, 2012 attacks were former Navy SEALs, 42-year-old Glen Doherty, of Encinitas, and 41-year-old Tyrone Woods, of Imperial Beach.
The attack also claimed life of information officer Sean Smith.
The families of the victims are scheduled to testify before the House Oversight and Government Reform Committee Thursday.
It's part of an 80-page report ordered by Democrats on the House oversight committee. The report also defends another review of Benghazi that was spearheaded by former U.N. Ambassador Thomas Pickering
House Democrats did find fault with the State Department for establishing Benghazi as a "temporary post" without the full security of an embassy or consulate.
State Dep't, GOP spar over Benghazi accountability
The Obama administration says it held four employees responsible for mistakes in the run-up to last year's Benghazi attack even though they are still working for the State Department.
Patrick Kennedy, the department's undersecretary for management, told the House Foreign Affairs Committee that relieving the four of their responsibilities and assigning them lower-profile jobs amounts to "serious accountability."
House Republicans rejected that assessment. Rep. Ed Royce, the committee chairman, said no one "missed a paycheck." Rep. Ileana Ros-Lehtinen said the department only shuffled "the deck chairs."
GOP members also raised several older complaints about the administration's handling of the Sept. 11, 2012, attack. They centered on the administration's initial explanations and why the military didn't intervene.
Several noted that a year after Benghazi, no militants have been brought to justice.