In the public's mind, Special Forces are often confused with the "door kickers" of Special Operations Forces -- such as SEAL Team 6 and Delta Force -- who are the United States' elite counterterrorism operators.
In fact, the primary mission of Special Forces, in particular the Army's Green Berets, who are profiled in the film, is to work "by, with and through" local forces on the ground to act as force multipliers. That means that Special Forces embed with local forces and work with them to achieve their common goals.
The Green Berets of US Special Forces 5th Group -- known as "the Legion" -- who led the anti-Taliban campaign represent a textbook case of a successful Special Forces campaign.
Five weeks after the 9/11 attacks, a 12-man Green Beret team led by Capt. Mark Nutsch was dropped into Afghanistan where they attached themselves to the army of the Uzbek warlord Gen. Abdul Rashid Dostum.
Riding horses into battle -- in a scene that could have played out during the American Civil War -- Nutsch and his team helped lead Dostum's forces to victory against the Taliban forces in the north of Afghanistan. Together, they rode into the key northern city of Mazar-i-Sharif on November 10 where they were greeted as liberators.
Meanwhile, in southern Afghanistan, Capt. Jason Amerine and his 12-man Green Beret team linked up with an obscure Afghan diplomat named Hamid Karzai.
In mid-November 2001, as they moved toward the city of Kandahar, the Taliban's de facto capital in southern Afghanistan, Amerine's team called in airstrikes against advancing Taliban units and more or less obliterated a Taliban column of a thousand men that had been dispatched from Kandahar. It was the Taliban's final play to remain in power.
The Taliban surrendered Kandahar on December 5 and the same day, Karzai was appointed to be the next leader of Afghanistan.
Few saw then that the United States would still be fighting wars of various kinds a decade and a half later, not only in Afghanistan, but also in Iraq and Syria.
Special Forces continue to play a key role in these wars, in part, because there is no demand signal today from the American public to send large conventional armies into the greater Middle East to fight wars against ISIS, al Qaeda and the Taliban.
This means American involvement in the wars in these countries must be conducted "by, with and through" the local forces on the ground, such as the Afghan army, Iraqi military and Syrian militias allied to the States. And that means a large role for US Special Forces, whose specialty is working with those local forces.
But this raises some serious questions about how much the American public is asking from its Special Forces, who are facing repeated deployments.
In "Legion of Brothers," Scott Neil, a Green Beret who was part of a sniper team in Afghanistan in the months after 9/11, explains: "You used to go into a VFW and you had one guy who had one tour. You were like 'Oh, wow.' You hear one guy had two tours. You're like 'Oh, he's a little crazy.' Somebody had three tours -- they're out of their minds. And what you see now is people have five, seven, nine, 10 tours. And they're still going."
This not only puts pressure on Special Forces but also, of course, puts much strain on their families. As Nutsch's wife, Amy, a special needs teacher and mother of four, puts it: "I've had some trying times at home, but managed to get through it. And then I yell at him later, going, 'This is what I have to deal with'."
There are no easy answers for how to reduce the pressures on the force and families in an era when there is a great demand for the skills that Special Forces bring to the battlefield.
Special Operations Command -- first under Adm. Eric Olson and then under Adm. Bill McRaven, the architect of the raid that killed Osama bin Laden -- put in place polices that emphasized more predictable deployments, allowing for more predictable blocks of time for servicemen to be with their families. They also started providing more support services for servicemen and their families.