(CNN) Regaining his senses, Matt Zeller checked his watch. It was 16:50, April 28, 2008. "[I thought] this is the day and the time and place I die," he remembered , years later.

At ten to five that afternoon, the US Army reservist was in the middle of the worst firefight he'd ever experienced, fourteen days in to a tour of Afghanistan. Low on ammunition and surrounded by dozens of Taliban fighters, bullets fizzed through the air and mortar rounds thudded near his position. One landed meters away, throwing Zeller into a neighboring ditch.

As he came around, he looked down at his timepiece. Then two things happened, almost simultaneously. AK-47 gunfire rang out and a body landed in the ditch alongside him. Clutching the weapon was Janis Shinwari, his Afghan interpreter, looking down its barrel at two dead Taliban fighters. If it wasn't for Shinwari, Zeller would likely have been shot in the back.

This extraordinary story is just one of thousands involving wartime allies; locals who have aided US forces abroad. But these men and women are so often those who are left behind when operations cease.

For his act of remarkable courage, Shinwari was placed atop the Taliban's kill list, threatening his life and those of his family. But removing them to safety in the US would take five years, Zeller told CNN -- in part due to the bureaucratic application process for a " Special Immigrant Visa ," which covers Iraq and Afghan wartime allies.

Zeller's efforts to secure Shinwari's future, appealing to the media, Congress and the Department of State, would result in him co-founding non-profit No One Left Behind in 2013, alongside Shinwari. It's also why CNN anchor and correspondent Michael Holmes selected the veteran for the " My Hero " series.

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No One Left Behind, as well as steering visa applicants through the process, provides after care for Afghan and Iraqi wartime allies, helping them set up their new lives in the US with homes, jobs and amenities.

"Since he started the group a few years ago, they've gotten out 4,000 translators and family members from Afghanistan and Iraq," Holmes explains. "The work he's doing is quite literally saving people's lives."

But, he adds, "there are still thousands and thousands more who have not gotten out."

Matt Zeller with Janis Shinwari after the translator landed in the US on October 29, 2014.

Numbers cleared for Special Immigrant Visas regularly surpass the number of visas available many times over. A State Department spokesperson told CNN that while there are more than 15,000 Afghans at some stage of the application process, as of March 5, 2017 only 1,437 visas were available.

This backlog has proven deadly for some.

"We have a running list of Afghan -- particularly Afghan -- but in some cases Iraqi visa applicants who died waiting for their visas," says Zeller on the phone, admitting that "it's a pretty regular occurrence."

The Department of State did not confirm to CNN if it held such figures, but Zeller says No One Left Behind has filed a formal request "to see if anybody is tracking it."

"We'll probably never know the true scale of it because it's not just the people who die at the hands of the Taliban and al-Qaeda and ISIS," Zeller adds.

"There's people who die because they were forced by those organizations to flee before they could get their hands on them," he says, citing the perilous crossing of the Aegean Sea taken by refugees moving from Turkey to Greece.

An Afghan man talks to a US Marine through an interpreter in Mian Poshteh, Afghanistan, July 14, 2009.

The State Department announced in a March 9 immigration bulletin that it "expects to exhaust" the Special Immigrant Visas allocated by Congress for Afghan allies "not later than June 1."

Furthermore, March 1 was the last scheduled date for applicant interviews of this category.

"[It's] night and day compared to even four months ago," Zeller argues. "We have a very hostile government who is going to continue to do whatever they can to scuttle this program. They have currently let the entire visa program in Afghanistan run out visas."

When queried by CNN, a State Department spokesman placed the onus on Congress to authorize more Special Immigrant Visas, saying it was ready to schedule more visa appointments in the eventuality.

When the Trump administration signed off on the first so-called 'travel ban' on January 27 (covering Iraq, Syria, Somalia, Sudan, Iran, Yemen and Libya) Zeller says sixty clients aided by No One Left Behind were affected -- 56 Iraqis and four Afghans (the latter detained by "overzealous immigration officers").

"We had two clients arrested upon arrival in the United States and detained for upwards of a day before they were finally released by a federal judge," he says.

"We had an entire family literally taken off their flight. They were on a plane in Turkey getting ready. They were on the runway. The plan was ready to take off -- I mean taxiing to take off -- when the plane was turned around and sent back to the airport. Turkish police entered the plane, handcuffed the husband, the wife, the three-year-old son and their nine-year-old daughter."

But, he adds, "these horrific experiences [...] really ignited a torrent of support."

"Over the course of that first weekend [of the first travel ban] we would receive in total around 3,000 pleas for help... but also the offers of 700 people to volunteer."

Zeller believes a number of military veterans protesting publicly against the first travel ban played a part in ensuring Iraq was removed from the banned list of countries when a revised executive order was signed March 6. "Trump saw that," he says. "He watches TV and he gets it."

CNN reported at the time that "intensive lobbying from the Iraqi government" had forced the move, and in remarks after the signing Secretary of State Rex Tillerson cited Iraq's "brave soldiers fighting in close coordination with America's men and women in uniform."

In the corporate world, No One Left Behind is gaining traction. Starbucks, for one, has allied itself with Zeller's group

"Starbucks, like we do, acknowledge their sacrifice and their effort is that of a veteran," he says.

But No One Left Behind still operates largely in isolation, particularly when it comes to helping Afghan and Iraqi families once they reach the US under Special Immigration Visas.

"The positive is in the last four years our organization has grown from an organization that started out in Washington D.C [...] to now having operations in eight cities across the United States on both coasts and in the heartland[s]," he says. "In addition, we're opening up another three chapters this year."

Zeller still has hopes that a program can be set up so that future US wartime allies won't have to look beyond the US government for help.

"We're a non-profit," he adds. "We should not be the United States' solution to this problem."