Five days after the attack, after feverish email exchanges about her "talking points" among national security staff members and their spokesmen, U.N. Ambassador Susan Rice linked the Benghazi attacks to protests in Tunisia and Cairo over an anti-Islam video. Weeks later, U.S. officials retracted that account but never fully articulated a new one.
Republicans seized on the inaccuracies, contending that the Obama administration was covering up a terror attack for political gain.
Several congressional and independent investigations have faulted the State Department for inadequate security, but they have not provided a full reading of who was involved in the violence, what the motives were and how they could pull off such a seemingly complicated, multipronged assault.
People on both sides of the debate tend to link the two incidents as one attack.
The congressional testimony that distinguishes the attacks came from military officials in Tripoli or, like Ham, coordinating the response in Washington. Most have never given a public account. But they agreed that confusion reigned from the outset.
"We're under attack," was the first report the military received from Benghazi. That message came from Stevens' entourage to Tripoli in the late afternoon of Sept. 11. Word was relayed to the defense attache, who reported up the chain of command.
That report gave no indication about the size or intensity of the attack.
The defense attache testified that the assault on the diplomatic mission was followed by a mob that complicated and confused the situation.
He said of the original attackers, "I don't think they were on the objective, so to speak, longer than 45 minutes. They kind of got on, did their business, and left." For hours after that, he said, there were looters and "people throwing stuff and you see the graffiti and things like that."
Once the first attack ended around 10 p.m., the military moved to evacuate Americans from Benghazi, while preparing for what it erroneously believed might have been an emerging hostage situation involving Stevens.
In fact, Stevens died of smoke inhalation after the diplomatic post was set on fire in the first attack.
Seven-and-a-half hours later, at dawn, mortars crashed on a CIA compound that had been unknown to top military commanders.
The military worked up a response on numerous fronts.
At one point, fewer than 10 U.S. military personnel in Libya were grappling with the mortar and rocket-propelled grenade attack on Americans who had taken cover at the CIA facility and, some 600 miles away, the evacuation of about three dozen people from the U.S. Embassy in Tripoli by a convoy of armored vehicles.
An unarmed Predator drone conducting an operation nearby in eastern Libya had been repositioned over Benghazi, yet offered limited assistance during the nighttime and with no intelligence to guide it. A standby force training in Croatia was ordered to Sicily, while another farther afield was mobilized. Neither was nearly ready in time to intervene during the first 45-minute attack and couldn't predict the quick mortar attack the next morning. An anti-terrorism support team in Spain was deployed, though it, too, was hours away.
American reinforcements of a six-man security team, including two military personnel, were held up at the Benghazi airport for hours by Libyan authorities. Drone images and intelligence hadn't provided indications of a new attack, but word eventually came from two special forces troops who had made it to the annex and reported casualties from the dawn attack up the chain of command.
In Tripoli, military and embassy officials were evacuating the embassy there and destroying computer hardware and sensitive information.
The administration last month apprehended its first suspect, Ahmed Abu Khattala, and brought him to the United States to stand trial on terrorism charges.