However, before the quartet took the stage, fans got a chance to understand the group and their ethos a little better through an emotional pre-taped package that explores each of their difficult and challenging experiences as members of the US armed services.
"I have nightmares. There are moments when I just begin to ball up and cry," Staff Sgt. Ron Henry tearfully explained in the moving clip. "There were times when I didn't think I would be able to handle this, and music was a great part of helping me cope with what I was dealing with."
"But there are so many Americans who are suffering in silence," he continued, referring to the thousands of men and women across the country struggling with depression, pain and PTSD. "This music that were doing can help them heal. That is what we live for every day."
For their semifinals performance, Voices of Service delivered a deeply emotional cover of OneRepublic's "Choke," and it proved to be a powerful, touching showcase for the range of their vocal talents and the depth of their emotional resonance.
The group was met with a loud, excited standing ovation from the audience, as well as the show's panel of judges, and Simon Cowell couldn't contain his admiration.
"On the night that matters, you do the most outstanding vocal that we've heard from you throughout the entire season," Simon marvels. "I know how much this means to you to be a part of the final, and you know what? You deserve to be there."
Meanwhile, Julianne Hough praised the "dynamics of their vocals," marveling, "You went from this intimate place to this eruption of beauty."
"But the best part is you put your purpose behind your passion, and that's undeniable," Hough added.
Guest judge Queen Latifah said she was "blown away" by the performance, and revealed why she connected with the group and their goals so closely.
"I think about my mom telling me about when she would have to wake my father up out of his nightmares from Vietnam," she shared on the show. "What your doing does have a purpose. It will continue to have a purpose and I hope to see you in the finals. But irregardless, keep doing what you're doing because you are saving and changing lives."
Speaking with ET's Denny Directo backstage after Tuesday's show, Queen Latifah explained why Voices of Service's performance and their message connected with her so strongly.
"I have a lot of family members who are veterans and who are serving right now, some are just retiring from the Air Force, from the Army. I got a cousin that's a ranger that's deployed," she shared. "They risk their lives for the safety and security of our country, but they go through a lot and when they come home they need to be supported 100 percent."
"We need to recognize they are living with a lot of things," she continued. "My dad sat me down one day and explained that to me, explained what he was going through and why there were so many challenges in our life. So I understand it and I understand that what VOS is doing really can go a long way in a person's life and can save their life."
Fans will find out if they will be one of the five acts moving on to the finals from tonight's second round of the semifinals during a special AGT results episode on Wednesday night at 8 p.m. ET/PT on NBC.