Nineteen years ago today (July 20, 2002), Toby Keith earned his ninth No. 1 single with his tune "Courtesy of the Red, White and Blue (The Angry American)."

Keith wrote "Courtesy of the Red, White and Blue" in late 2001, as a response to the 9/11 terrorist attacks and also as a tribute to his father, Hubert Covel, who was killed in a car accident in March of that year. The tune, which Keith says he penned in about 20 minutes, was the debut single from Keith's multi-platinum, No. 1 album Unleashed. The singer originally wrote "Courtesy of the Red, White and Blue," which also peaked at No. 25 on the Billboard 100 chart, only for himself to play for the troops overseas -- but he had a change of heart.

"It wasn't written for everybody," the Oklahoma native tells CBS News. "And when you write something from your heart -- I had a dad that was a veteran, taught me how precious our freedom is -- I was so angry when we were attacked here on American soil that it leaked out of me. You know, some people wept when they heard it. Some people got goosebumps. Some people were emotionally moved. Some cheered, turned their fists in the air."

Toby Keith Red White and Blue

"Courtesy of the Red, White and Blue" wasn't well received by everyone, however: Keith was removed from the lineup for a patriotic TV show on ABC when he refused to either soften the lyrics or choose another song with which to open the televised special. But the biggest controversy surrounding the song came from the Chicks, when lead singer Natalie Maines spoke out publicly against the track's lyrical content.

"I hate it," Maines said at the time. "It's ignorant, and it makes country music sound ignorant. It targets an entire culture -- and not just the bad people who did bad things. You've got to have some tact. Anybody can write, 'We'll put a boot in your ass.'"

Keith responded by showing a backdrop of Maines edited into a picture with Saddam Hussein during his concerts; Maines countered by wearing a T-shirt that said "FUTK" at the ACM Awards.

Controversy aside, "Courtesy of the Red, White and Blue" is one of the biggest hits of Keith's career. It was certified gold, signifying sales in excess of 500,000 units, and helped his Unleashed album earn the American Music Award for Favorite Country Album. It also helped score Keith the ACM for Entertainer of the Year.

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