"U.S. ambassadors are not required to consult or seek approval from Washington, when traveling within their countries, and rarely do," she wrote.
"Like all chiefs of mission, Chris made decisions about his movements based on the security assessments of his team on the ground, as well as his own judgment," she said. "After all, no one had more knowledge or experience in Libya than he did. He was well aware of the lawlessness in Benghazi, including a series of incidents earlier in the year against Western interests. Yet he understood Benghazi's strategic importance in Libya and decided that the value of a visit outweighed the risks."
So, what exactly was the "value of the visit"?
The Senate Select Intelligence Committee published a report on Jan. 15 of this year -- about five months before Clinton published her book -- indicating that the intelligence community had warned of the growing terrorist threat in eastern Libya.
"On June 12, 2012," the intelligence committee said, "the Defense Intelligence Agency (DIA) produced a report entitled, 'Libya: Terrorists Now Targeting U.S. and Western Interests.' The report noted recent attacks against the U.S. Mission compound in Benghazi, the growing ties between al-Qa'ida (AQ) regional nodes and Libya-based terrorists, and stated: 'We expect more anti-U.S. attacks in eastern Libya [redacted] due to the terrorists' greater presence there.'"
On Aug. 16, 2012, according to the committee, Amb. Stevens sent a cable to State Department headquarters describing the Emergency Action Committee that had convened in Benghazi the day before.
Stevens said a CIA officer had "briefed the EAC on the location of approximately ten Islamist militias and AQ training camps within Benghazi."
Stevens also said the department's Regional Security Officer had "expressed concerns with the ability to defend Post [in Benghazi] in the event of a coordinated attack due to limited manpower, security measures, weapons capabilities, host nation support, and the overall size of the compound."
So, why did Stevens go there?
Gregory Hicks, who served with Stevens as the deputy chief of mission at the U.S. Embassy in Tripoli, told the House Oversight and Government Reform Committee in a May 8, 2013 hearing that one reason was that Clinton wanted to make Benghazi a permanent U.S. diplomatic mission.
He also noted that Clinton (who had already indicated she did not intend to serve in a second Obama administration) intended to visit Tripoli in December 2012.
"Chris told me that in his exit interview with the secretary after he was sworn in, the secretary said we need to make Benghazi a permanent post. And Chris said I will make it happen," Hicks testified.
Rep. Doug Collins, R-Ga., asked Hicks: "Was Washington informed of the ambassador's plan to travel to Benghazi?"
"Yes. Washington was fully informed that the Ambassador was going to Benghazi. And we advised them August 22nd or thereabouts," said Hicks.
"Were there any concerns raised from that?" asked Collins.
"No," said Hicks.
"Given the timing and everything?" asked Collins.
"None," said Hicks.
Rep. James Lankford, R-Okla., also asked Hicks: "Why was the ambassador headed there?"
"According to Chris, Secretary Clinton wanted Benghazi converted into a permanent constituent post. Timing for this decision was important," said Hicks. "Chris needed to report before September 30th, the end of the fiscal year, on the physical and the political and security environment in Benghazi to support an action memo to convert Benghazi from a temporary facility to a permanent facility. In addition, Chris wanted to make a symbolic gesture to the people of Benghazi that the United States stood behind their dream of establishing a new democracy."
"We had funds available that could be transferred from an account set aside for Iraq and could be dedicated to this purpose," Hicks explained. "They had to be obligated by September 30th.
"And where did those instructions come from?" Lankford asked.
"This came from the executive office of the Bureau of Near Eastern Affairs," said Hicks.
Hicks also told Lankford the timing of Stevens' trip helped fill a gap in the staffing of the principal officer position at the Benghazi mission.
Rep. Thomas Massie, R.-Ky., asked Hicks: "Did you tell the Accountability Review Board about Secretary Clinton's interest in establishing a permanent presence in Benghazi? Because ostensibly wasn't that the reason that the ambassador was going to Benghazi?"
Hicks said: "Yes, I did tell the Accountability Review Board that Secretary Clinton wanted the post made permanent. Ambassador [Thomas] Pickering [chairman of the ARB] was surprised. He looked both ways to the members of the board, saying does the seventh floor know about this? And another factor in Chris' decision was our understanding that Secretary Clinton intended to visit Tripoli in December."
The intelligence committee report included information from the CIA's Chief of Base in Benghazi that backs up the conclusion that CIA and State were planning to "co-locate" at a new facility in Benghazi (which would have brought the State Department into compliance with one of the requirements of the Secure Embassy Construction and Counterterrorism Act enacted after the 1998 attacks on the U.S. embassies in Kenya and Tanzania).
"The Chief of Base stated that there had been discussions with Ambassador Stevens about co-locating the Annex and the State Department compound at the same facility," the committee reported.
"We had our officers come out there to survey different locations in Benghazi to look for a location that we could co-locate with the State Department, and we were planning to do that before the end of this  calendar year," the Chief of Base said, according to the report. "So there absolutely was a plan to do that."