As she began her testimony, her voice cracked at times as she said her work is sometimes highly personal, she told the Senate Foreign Relations Committee:
I stood next to President Obama as the Marines carried those flag-draped caskets off the plane at Andrews. I put my arms around the mothers and fathers, sisters and brothers, sons and daughters.
At another point, she defended UN Ambassador Susan Rice, who was vilified for widely debunked claims five days after the attack that protests precipitated the raid rather than terrorism. She challenged the Republican focus on Rice's comments, which were based on intelligence talking points.
"What difference does it make?" a clearly exasperated Clinton told Sen. Ron Johnson, a Republican, after he pressed her. She insisted that "people were trying in real time to get to the best information," and that her focus was on looking ahead on how to improve security.
More top news
Thirty facts about Prince Harry to celebrate his coming of age.
Django Unchained actress Danièle Watts was handcuffed by police after she was seen "showing affection" to her partner, NBC News reported.
A US news anchor has told viewers he only has four to six months to live on air, after he was informed that his brain tumour was inoperable.