Like a proverbial snowball careening down a hill, The War and Treaty seems to get bigger and gain momentum on a regular basis.

The soulful husband-wife duo that formed in Albion 11 years ago has only seen that roll accelerate during the past five years. Named the Emerging Artist of the Year at the 2019 Americana Music Honors & Awards, Michael and Tanya Trotter have been fully embraced by the Nashville music community, winning more Americana honors (Duo/Group of the Year in 2020 and 2023) and Folk Alliance International’s Artist of the Year in 2020 and named one of Billboard magazine’s Country Power Players.

It’s also the first Black act nominated for the Academy of Country Music Award’s Duo of the Year and was up for Best New Artist at last year’s Grammy Awards — a decade, four albums and two EPs into their career. “I always say we’re new to somebody,” Tanya says with a laugh via Zoom from the couple’s home in Nashville.

At this juncture, however, the Trotters have a bead on what’s bringing and maintaining an audience that includes peers such as Zach Bryan, Dierks Bentley, Brothers Osborne, Jon Bon Jovi, Josh Groban and Miranda Lambert, who have all collaborated with them.

“We preach love, that’s it,” explains Michael, a Cleveland native and military veteran who’s been open about struggles with PTSD that inform some of the duo’s songs. “We believe in love. We want to see more love. We want to feel more love. You can pass a bill or you can come with posses and all those things, but at the end of the day, love is the only thing that matters. As long as we stay true to who we are, we’re gonna always be around.”

Tanya, who hails from Washington, D.C., and appeared in the 1993 film “Sister Act 2: Back in the Habit,” agrees that “that’s the foundation of what The War and Treaty is all about, is people. People make this thing go around. If we stop being people, everything shuts down. If we stop having love and faith in each other, everything stops. So that’s what our job is.”

The War and Treaty certainly went to work on its latest album, “Plus One.” Released on Valentine’s Day and produced primarily by Michael, the set — recorded at legendary FAME Studios in Muscle Shoals, Alabama — features a whopping 18 songs and the most diverse array of music the duo has put on record yet. Its 67 minutes roll through the old-school soul of “Stealing a Kiss” to the stomping gospel of “Can I Get an Amen,” the down-home country of “Leads Me Home,” the torchy country soul of “Carried Away” and the brassy New Orleans gallop of “Call You By Your Name.”

Elsewhere, The War and Treaty tries to drive riffy rock in “Tunnel Vision” and gets assistance from fellow Michigander Billy Strings on “Drink From Me.” Michael, a longtime Bone Thugs-n-Harmony fan, busts some rhymes on “I Can’t Let You Go,” while Tanya channels a Dionne Warwick-worthy performance into “Teardrops in the Rain,” and Celtic overtones add to the triumphant cadence of the album-closing “The Glorious Ones.”

“We wanted to challenge ourselves, to widen the perspective, musically,” acknowledges Michael, putting his arm around Tanya on the couch they’re sharing. “We have different styles. We collaborated with different individuals — and I do mean different. But at the end of the day, we all had the same aim, just doing what we all love.”

The War and Treaty’s comfort zone was indeed stretched throughout the project — from the get-go. The opening track, “Love Like Whiskey, is a songwriting collaboration with Lambert, who the Trotters found surprising in the best possible way.

“She is a genius,” Tanya gushes. “I don’t think people think of her as a vocal producer, immediately, but she knows exactly what wants the song to say, exactly how she wants you to produce the song. She was brilliant. Not that I didn’t expect it of her, but it’s a side you don’t get to see outside the studio, when you’re chatting with her on text message and stuff like that. I learned a lot from her in that session.”

Michael, meanwhile, laughs as he notes: “Miranda is dangerous. You don’t see her coming. It’s so much fun being in the studio with her, ’cause she’s a drinker, and you’ll be drinking and laughing and then she’s like, ‘OK, on this line, we’re gonna do this …’ and she’s right back in it. That’s her superpower.”

Working at FAME, Michael says, “was life-changing. You got the spirit of Aretha (Franklin) and Wilson Pickett and the Allman Brothers.” But at the heart of “Plus One,” however — as on The War and Treaty’s other work — is the vocal and lyrical exchange between the Trotters, a dialogue that celebrates devotion and dedication, acknowledging both good times and bad but with resolve to come out better on the other side — and idea embodied in songs such as the soaring “Home” from “Plus One.”

“I think it’s very conscious to make sure it sounds like what you sounded like coming out of that Baptist church choir or singing in that Seventh Day Adventist church, making sure the grit is there, that soul is there, that good news that comes out of your voice when you’re singing the gospel,” Tanya explains. “We don’t want to shy away from the grit and growls and the passion of that.”

“Conversational” is also a word the two use to describe the way they sing together. “When you’re raised in a singing family, it’s not that odd,” Michael notes. “Tanya sang with her brother. I sang with my mom and my siblings and my aunt. So we just brought that back to this space — ‘Let’s have a conversation again.’ And throughout this process, I’ve learned to fall in love with that particular thing.”

“Plus One” is putting The War and Treaty back on the road, starting Wednesday, March 26 in Minneapolis and including home state tops on Friday, March 28 in Grand Rapids and the next night at Detroit’s Saint Andrew’s Hall, where they’ll be filming and recording the concert. The duo will be opening for Chris Stapleton in June, as well. The Trotters also have started their own management company “to facilitate the whole vision we have for ourselves” according to Tanya, which includes expanding its Hearts Town Facebook community into a full-fledged website.

The Trotters also are launching initiatives for men’s health and military veterans, while Michael has “some special songs coming out” on upcoming releases by Billy Strings and Wynonna Judd.

“All of this has been life-changing,” Tanya says. “You always think about your fans, but when you have your peers, like Wynonna or Bon Jovi, that really transcend time and genre, or when Vince Gill stands up for us, in his Vince Gill way, when someone said something that wasn’t nice about us … it’s just pretty amazing that people are willing to offer up their platforms for you and give you these great opportunities.

“That opens your heart on so many levels. And it’s a teaching moment for us, as well, so we can do the same things for artists coming up behind us.”