The day that began with him jogging in Florida ended with the country changed forever, facing a different kind of enemy.
"September the 11th affected my presidency, and it caused … it caused me to make many decisions. Some of which were extremely controversial. All of which were designed to protect the homeland. I didn't have a strategy. I was living day by day," he said.
After the attacks, he pledged to hunt down Osama bin Laden, the mastermind, but critics have said he failed to make that a top priority of his presidency.
Bush discussed his reaction to news that the 9/11 mastermind had been killed by U.S. special forces on May 1. He had been having dinner with his wife in a restaurant when he received word that President Barack Obama would be calling him.
"I decided to take the call at the house. And President Obama called me, told me that Osama bin Laden had been killed. And my response was, I congratulated him, and the special operators that conducted a very dangerous mission.
"And so I was grateful," he added. "I didn't … feel any great sense of happiness. Or jubilation. I felt a sense of closure. And I felt a sense of gratitude that justice had been done."
"Eventually September the 11th will be a date on the calendar, it'll be like Pearl Harbor day. For those of us who lived through it, it'll be a day that we'll never forget."