Country music singer Toby Keith died on Monday. He was 62.

While Keith signed his first record deal in 1993, he became better known outside the country music orbit after the Sept. 11, 2001, terrorist attacks when he released the hit song “Courtesy of the Red, White and Blue (The Angry American)" in 2002. The rally-around-the-flag anthem captured the rage Americans were feeling after the attacks on the World Trade Center and the Pentagon with explicit lyrics like “you'll be sorry that you messed with the U.S. of A / 'Cause we'll put a boot in your ass, it's the American way.”

Keith came up with the idea for the song the week after 9/11. He was organizing his fantasy football team and started scribbling the lyrics on the back of a sheet of paper. According to a Mar. 1, 2004 profile of the singer (headlined "America's Ruffian") in TIME, the song "tumbled out of him in a 20-minute writing binge."

"‘I wrote it so that I had something to play for our fighting men and women,’ he says. In a trial run at the U.S. Naval Academy, it brought the house down. ‘But once people said I should release it, I knew there was going to be trouble. I'm comfortable being extreme, but saying 'boot in your ass' is so extreme. Of course, if you say, 'foot in your butt,' you got no song.’”

In a 2003 60 Minutes interview, Keith said he hoped to perform the song for troops deployed abroad in the Middle East, so he played it for Pentagon officials. He said a Marine Corps commandant urged him to release the song globally, arguing that it would be a public service.

The song was a hit, and peaked at #25 on the Billboard chart of the hottest songs in the U.S. At least one tank in Baghdad had “Courtesy of the Red, White, and Blue” written across it. That 2004 TIME profile dubbed Keith “the poet laureate of righteous indignation” and the “country's resident rogue--the permanent outsider who speaks manly but unwelcome truths.” But the gung-ho tone of the lyrics didn’t mean that he agreed with everything about the war in Iraq, describing himself politically to the magazine as “an extremely conservative Democrat” with mixed feelings about the motivations for the war with Iraq. That said, he told the magazine, "Most people think I'm a redneck patriot. I'm O.K. with that."

But the angry lyrics in the song rubbed some the wrong way. Keith was set to perform the song for a 2002 July 4th special hosted by Peter Jennings, but Jennings reportedly nixed the idea because he thought the song wouldn’t set the right tone. In subsequent years Keith maintained that he had no regrets and said that the song had to be provocative to boost national morale. As he put it in a 2021 FOX Nation interview, “I knew it would be polarizing, I knew it would be a lightning rod. And I prayed about it. But at the end of the day, it was a battle cry for our guys to go win and get back home safely and go do what Americans really do.”