Together, The War and Treaty’s Michael and Tanya Trotter have been releasing albums – and mastering their soulful blend of gospel, blues and country music – for the better chunk of a decade. But the past year has brought a wave of milestone moments for the husband-and-wife duo, from signing their first major record deal with Universal Music Group Nashville and releasing Lover’s Game in March, to seeing their streaming numbers multiply by the millions overnight, after teaming up with country’s latest chart-topping megastar, Zach Bryan, on the single ‘Hey Driver’.

“People are writing to us, saying, ‘Wow, we just discovered you – where have you been?’” Michael tells me, laughing through his jetlag in the front bar of The Workman’s Club in Dublin, a few hours before their headline show. “I’m like, ‘Where have I been?!’

“Everyone’s making such a big fuss about this song,” he says of 'Hey Driver'. “It’s interesting, because all I thought was, ‘This is cool, we get to do a song with Zach.’ We met him not that long ago, but it’s apparent that he’s got something happening over on his side, that we don’t have on ours. We needed some of that influence – and he gave us all the influence in the world.”

It’s a particularly sweet victory for the couple, who have endured more than their fair share of hard times together.

“At one moment in the early part of our marriage, we were homeless, and we were living in a shelter, in Richmond, Virginia,” Michael recalls. “This shelter had a bay window, and I had this little Casio piano. Our son had been born not that long before, and while Tanya was nursing and holding him, she said, ‘Play for me.’ So I sat by the window, with the rain coming down, and the sun setting, and I played. I think that was the longest I’ve ever played. I played all night long, and she slept with the baby, so peacefully.”

Despite the pair having opened for the legendary likes of Al Green, Van Morrison, Brandi Carlile, Jason Isbell, Chris Stapleton, and John Legend, that memory remains a highlight for Michael: “It’s one of my favourite moments in my history of being a pianist.”

Michael first connected with the piano while serving in the Army, in Iraq. He was stationed in one of Saddam Hussein’s former palaces, which happened to have an upright piano in the basement. It was a crucial form of respite, as those around him, including his captain, were killed.

He’s been open about his struggles with PTSD in the years since.

“I write because I want the person who’s like me to know that they’re not alone,” he remarks. “That would mean that we’re using our story to do good – by putting myself out there, and saying, ‘Hey, I was once suicidal, and I struggle with my mental health from time to time.’

“I also write because my wife told me I could,” he adds. “Love dug me out of that hole. My confidence wasn’t what it should have been. Then I met Tanya, and I started to find my confidence again, through her boosting it.”

As Tanya explains, it was music they bonded over initially, when she first saw him perform.

“But once I met him, we connected as human beings,” she resumes. “We talked for hours about things that had nothing to do with music.

“We would see a deer out on a road, losing its life, and both of us would be crying, trying to save the deer,” she continues. “We both had a compassion not just for humanity, but for everything. Everything that breathes, we can feel it.”

She stops herself, and doubles back: “Well – except Michael and dogs…”

“It’s not that I don’t like dogs!” Michael protests, laughing. “I have a discomfort around big dogs…”

“Okay, so we’ll get a little dog!”

Clearly, their chemistry as a duo marks them as a special force – but it was while living in Albion, Michigan that their genre-transcending sound really began to take shape.

“There’s a little venue there, Blues at the Bohm, where the musicians in town would come together, and play blues jams,” Tanya tells me. “Of course we knew the blues – but at this place, blues was their thing. We became part of that scene, which pushed us into blues, and mixing that with our gospel sound.

“I was born and raised in the church,” she adds. “I was a Baptist, floor-stomping, tambourine-having, choir-robe-wearing singer!”

They were also following in the footsteps of legends like Ray Charles with that genre-blending approach.

“Ray Charles took what we all grew up on, gospel music, and infused it into country music,” Tanya explains. “It was the same way for us. We’re taking what we know, and fusing it in our way with all the different sounds we love.”

The War and Treaty are now based in the capital of country music, Nashville, Tennessee – and have been recognised there by major institutions like the Country Music Hall of Fame and the Grand Ole Opry.

“It feels like the wave of change is happening,” Michael says of their position in the country world. “Whatever you thought of as the perfect model of a country music star, you now have to consider that maybe that’s wrong. You have to broaden it. And it feels good to be in that convo.”

Of course, we’re also currently seeing America’s culture wars playing out dramatically in the realm of country music – with country songs topping mainstream charts and sparking controversy in equal measure. Newcomer Oliver Anthony, for instance, has been hailed as a deeply authentic working class voice by some, but his lyrics that have been perceived to be anti-welfare have been blasted by others.

“In the United States, we’re seeing a strong wave of defiance, and establishment-bashing,” Michael considers. “It doesn’t serve a purpose, other than to defy, or to stand up and become disagreeable. There’s no solution that they’re after.

“But these artists are just being themselves,” he continues. “Authenticity gets the reaction. And oftentimes, what people really want is an authentic reaction that’s in alignment with their own. They want to support other people who think and feel like them.”

But, as Michael points out, “There’s some amazing artists out there who deserve that exposure and that platform – and they just talk about love.”

“Leon Bridges is one, and Gregory Porter, and Samara Joy,” he resumes. “They should be just as big, if not bigger. Because they are solutions to our questions like: ‘Where’s Miss Nina Simone? Where are the Nat King Coles?’”

The pair have also got some notable Irish names on their radar.

“I love Glen Hansard,” Michael says of the Dublin singer-songwriter, who he first discovered through the film Once. “I love that man, straight up!”

“We sang with him at the Newport Folk Festival,” Tanya adds. “And I video-taped Michael singing, because I knew he had wanted to sing with Glen so much. It was really nice to watch them together.”

“And I have some other interests in Irish culture!” Michael enthuses. “Becky Lynch and Sheamus rule WWE wrestling right now. Becky’s the man! I want to get drunk – and sing! – with them.”

For now, The War and Treaty are largely focused on the unfurling road ahead – writing new songs on the go as they tour with their children in tow, and remaining “always in the music.”

“I couldn’t do this without him,” Tanya tells me. “I wouldn’t be sitting in front of you if I was a solo artist.”

“And as you can see, I definitely couldn’t do it without her,” Michael laughs, slumped over in dramatic tour-related exhaustion. “Hold me up, honey!”

• The War and Treaty’s collaboration with Zach Bryan, ‘Hey Driver’, is out now.