The Zac Brown Band performed the song "Dress Blues," from their upcoming Jekyll + Hyde album, during a recent appearance on Jimmy Kimmel Live.

The poignant tune, with lines like, "Mamas and grandmamas love you / American boys hate to lose / You never planned on the bombs in the sand / Or sleeping in your dress blues," was written by Jason Isbell, for his 2007 Sirens of the Ditch album, as a response to finding out that a former schoolmate had been killed in the Iraq War.

"I was coming off a tour with the [Drive By] Truckers, and I called my mom, and she told me about his funeral, which she'd attended that day," Isbell recalls. "When I got home, I wrote "Dress Blues" in [the] time it takes to write it down on a piece of paper. I already had the chord progression from a song [I'd] been working on about Mickey Rooney, of all things. The song just fit that tune."

In addition to their single "Homegrown," the Zac Brown Band have shared one other song that will appear on Jekyll + Hyde. The Georgia-based group performed "Heavy Is the Head," which features Chris Cornell, during an appearance on Saturday Night Live earlier this month.

Zac Brown has hinted that Jekyll + Hyde will be different than any of the band's previous records.

"We're all continuing to grow up and get better as musicians and the chemistry as a band continues to deepen," Brown reveals. "Our boundaries have dissolved and we're going to still do things that are somewhat familiar that people like, but we're also going to stretch out and take chances beyond what we've done before. Some people are going to be really surprised."

Jekyll + Hyde will be released on April 28. It is available for pre-order on Amazon and iTunes.

See Zac Brown's Yearbook Picture!