He didn't even really hear an explosion -- just a "pop" in his damaged ears.
But there was one thing he could hear, loud and clear, as he lay on the ground in a cloud of ammonia and with bones sticking out of his shattered leg: The Taliban, celebrating and congratulating one another over intercepted radio traffic, on what they thought was the death of an American soldier.
The memory of their laughter drove Hendrickson over the following 18 months, as he defied the odds to save his leg, recover both physically and emotionally, and then in 2012 return to Afghanistan for several more deployments, eventually earning a Silver Star.
"My mindset was, you bloodied me up, and you hurt me, but you didn't beat me," Hendrickson, who retired as a sergeant first class in 2020, said in an August interview. "And I'm coming back."
Hendrickson was just one of many who experienced trauma, but he signed up to head back into a campaign still going years after his injury in what became a new normal -- 20 years of constant war.
The war in Afghanistan -- by far the longest in U.S. history -- is all but over, aside from the frantic evacuation of tens of thousands of Americans, Afghans and other civilians from the Hamid Karzai International Airport in Kabul.
But it has changed the U.S. military, in ways that will linger. Those who saw the war up close -- including veterans of Afghanistan and current and retired generals and senior officials -- agree that the war didn't break the military. But it did bend it, testing the men and women sent to fight, and the weapons and hardware they relied upon to survive in Afghanistan's harsh regions.
Retired Gen. Joe Votel, who headed both U.S. Special Operations Command and U.S. Central Command, saw "the fraying of the force" that resulted from the numerous deployments special operators shouldered.
After the invasion of Afghanistan in 2001, continual war became a regular part of life for the military, even normalized, in a way it never had before -- or was meant to. When death, trauma, family separations and other sufferings inherent to conflict became part of the day-to-day, the effects on the military extended to everything from family strife to physical and mental wounds. In some rare cases, most notoriously Army Staff Sgt. Robert Bales' 2012 massacre of 16 Afghan civilians, that shift to the mundane included a blurring of morality and the lines separating the good guys from the bad.
It led the military to refine the ways it fights and resulted in unprecedented advancements in tactics, technology, medical treatments and equipment.
But it also took a significant toll on the force. There were 2,448 U.S. service members killed in Afghanistan, and at least 20,722 wounded, some of whom will deal with those injuries for the rest of their lives. For some of the troops who deployed, it led to trauma, struggles with mental health and moral injuries, and strained family lives.
That is a price the military has not yet fully reckoned with; it is still struggling to figure out how to do so.
"When you deploy people into continuous combat operations, they're going back to Afghanistan, or back to Iraq, or they've been there multiple times, sometimes they have a tendency to develop the attitude that, 'I have done this before, I know what I'm doing,'" Votel said. "And so they become a little bit detached from the situation. And that's where you begin to have some of these challenges. People forget about the human aspect of this. ... They forget that they're dealing with people on the ground."
The act of taking a life, or firing weapons where civilians are nearby -- the sorts of moral decisions that can be incredibly difficult -- became normal.
"The things that aren't supposed to be routine, become routine, and then you begin to think of them as routine," Votel said. "That's something you really have to guard against."
The Toll of the Conflict
The war exposed some of the military's vulnerabilities, including the alarming growth in deaths by suicide, which have claimed more than four times as many troops and veterans post-9/11 than actual combat -- and how special operators' long and repeated deployments affected them and their families.
In January 2020, in the wake of multiple troubling and embarrassing incidents, Special Operations Command released a "comprehensive review" of its force that concluded the community had grown a culture that prioritized deployments and getting the job done above all else, leading to an environment where ethical lapses could happen.
Votel said the Ranger Regiment dealt with this problem by more aggressively telling Rangers to "sit this one out."
It's often not easy for them to receive the message that they should skip a mission.
"That's why these people join; that's what they want to do," Votel said.
Russell Parker, a Marine Raider who repeatedly deployed to Afghanistan and retired as a lieutenant colonel in June, said there's no question deployments take a toll on families. He was in Afghanistan nearly 11 years ago when his daughter was born, while a family friend was by his wife's side. He met his daughter after he got home, but then left again on another deployment just after her third birthday -- and he said his deployment burdens were light compared to others he served with.
"If you're a guy or gal who's deployed every 12 or even 24 months, for six to 12 months, that's a whole lot of missed birthdays," Parker said. "Which leads to a huge burden on the stay-at-home spouse. ... And either the family can absorb that, or over time, they decide we just can't [and] they have to move on without you."
It was the special operations community and the Air Force that were most consistently called upon to fight on Afghanistan's rocky, dusty terrain, and in the skies above. The cost of that near-constant combat added up.
Aside from the initial invasion of Afghanistan and periodic surges, such as former President Barack Obama's surge that began in 2009 and relied heavily upon conventional forces, special operations troops bore the heaviest burden of the war, said Wesley Morgan, journalist and author of "The Hardest Place: The American Military Adrift in Afghanistan's Pech Valley."
The reliance on special operations forces in Afghanistan was, in many ways, a double-edged sword, Morgan said. It dealt a significant amount of wear and tear on them, physically and mentally.
But Afghanistan was also a crucible for special operations, in which forces like the Rangers grew in size, responsibilities and capabilities.
The special operations force is "simply unrecognizable from what it was before," Morgan said. "It's so much larger, its capabilities are so much greater. Its combat experience is so much greater, by orders of magnitude, than anything that was there before. And by the same token, of course, the wear and tear is greater as well."
Special operators were in Afghanistan practically constantly from 2001, training Afghan troops, building relationships with village leaders, and going on missions against everyone from the Taliban to al-Qaida to the Islamic State offshoot ISIS-Khorasan.
That "never say no" mindset carried a significant price, in deaths, woundings and the mental toll of deployment after deployment.
The military didn't see "complete, total meltdowns" in special operations organizations due to the high pace of deployments, Votel said -- partly because it recognized the stress it was placing on troops and took steps to better control deployments.
"Maybe we should have done that earlier, a little bit more effectively early on," Votel said. "But I don't think we brought organizations to their knees."
For decades, the military culture had been reluctant at best to encourage troops to look after their mental health properly. Parker said the tremendous mental health needs caused by the war in Afghanistan -- along with shifting generational attitudes toward mental health -- forced a sea change in how the military addresses it.
Programs such as Preservation of the Force and Families -- which brought psychologists, social workers and other mental health professionals into direct contact with special operators to help them deal with the pressures of deployment and the injuries they sustained -- helped, Parker said.
Now if someone is in trouble, he said, "it's all hands on deck. I've got a military family life coordinator, I've got a social worker, I've got a psychologist, I've got a chaplain, I've got an MD -- pick a modality of treatment, and I've either got them sitting around the table with me to advise me on that person right now ... or I have the ability to reach out and find the discipline I need.
"We saved lives with that," Parker said. "We literally arrested suicide[s], right before they happened by getting these reviews done."
War as Opportunity
Perpetual combat wore on both man and machine, but it also served as an unprecedented testing ground. The conflict spurred extraordinary advancements in many elements of fighting war -- everything from tactics and technology, to how the military talks about and treats both mental health and physical wounds, which helped save Hendrickson's leg and allow him to return to the battlefield.
"I don't think there's any question that tactical-level, individual soldier, Marine, sailor, airman, skills are light years beyond where they were when I joined the Marine Corps in 1994," Parker said. "The advances in equipment, the advances in capabilities, the advances in tactics, techniques and procedures ... you almost can't discuss them in the same conversation."
Things like drones went from military afterthought to critical hardware.
"Look at drone technology and where we [were] in 2001, and where we've ended up," Votel said. "You see more and more effort now, of people reaching out and really grabbing onto technology and helping them leverage our ability to pursue our national security objectives."
Over the years in Afghanistan, the Air Force refined its process for delivering airstrikes, with munitions guided to their targets by troops on the ground. Scores of Air Force award citations since 2001 describe the heroism of airmen under heavy fire, simultaneously calling in airstrikes while firing back at Taliban or other foes, sometimes as they helped wounded teammates or while they themselves were injured.
Morgan said the growth of a generation of Army soldiers who came in shortly before or after 9/11, many of whom deployed repeatedly to Afghanistan, has resulted in a cadre of battle-tested leaders, the likes of which have not been seen since Vietnam.
"Afghanistan comes up over and over and over and over again," Morgan said. "The sheer length of experience that certain parts of the Army, in particular light infantry units and the Rangers, have had in Afghanistan really means that for all of these senior leaders, for the infantry in particular, Afghanistan has been a formative experience at many points in their careers and lives. ... If you have stayed in the Army, you've done Afghanistan."
Hendrickson points to the considerable strides made in medical care -- particularly in treating trauma and saving severely damaged limbs -- that resulted from the war, and saved his own leg.
After his teammates rescued him -- and after hearing the Taliban's rejoicing at his wounding -- Hendrickson flew to the hospital at Landstuhl Air Base in Germany.
When they transferred him to Brooke Army Medical Center in Texas, he was warned he likely would lose his leg.
"I just had a chunk of meatloaf down there," Hendrickson said, not to mention E. coli from the Helmand River. He tried to prepare himself emotionally for life with one leg by placing his undamaged left leg outside his hospital bed covers, and hiding his right leg up to the knee with the blanket.
His right leg will never again be what it once was. But the Intrepid Dynamic Exoskeletal Orthosis, or IDEO -- a brace that provides more support to his damaged leg -- allows him to run, carry heavy loads of gear on a march, or drag wounded teammates out of the line of fire. Without that brace, which he wore on his deployments beginning in 2012, he might have had to have his leg amputated if he wanted to do much beyond walking around the house.
"So many people are getting a second chance at saving a limb," he said.
Flying Aircraft to the Edge
The strain of the war also began to materialize on the Air Force in recent years, as airframes showed their age and airmen found it harder and harder to keep them flying.
The B-1B Lancer bomber in particular, which now has an average age of more than 33 years, became "overextended" in the Middle East, Air Force Global Strike Command head Gen. Timothy Ray said in 2019.
"We saw issues in the B-1 because we're just beating the heck out of them, deploying them, deploying them," Vice Chairman of the Joint Chiefs of Staff Gen. John Hyten told lawmakers during his nomination hearing in August 2019. At that time, Hyten said, just six B-1s out of the fleet of 62 were fully mission-capable.
Though those numbers recovered somewhat, they were still far from where they should be. In 2019 -- the latest year for which statistics are available -- the Air Force recorded a 46% mission-capable rate for the B-1, meaning at any given time, less than half of the fleet was ready to fly and carry out missions.
While that problem may not have been as severe in other airframes, it was a common issue throughout the fleet in recent years as the Air Force conducted a sustained air war, Gen. Herbert "Hawk" Carlisle, who was head of Air Combat Command until his retirement in 2017, said in a July interview. Fighters, bombers, surveillance aircraft, tankers -- practically no type of aircraft was unaffected.
"We flew the wings off of every platform, whether it was AWACS, or JSTARS, or Rivet Joints, or F-15s and F-16s, or B-52s, or KC-135s and KC-10s," Carlisle said. "Did we run them ragged in the Middle East? Yeah. Did they step up? More than you can ever imagine. What our young women and men did in uniform across all the services is extraordinary."
In an Aug. 13 interview, Ray acknowledged the toll so much air combat has taken on his bombers -- but said it's what they were meant to do.
"The safest place for an airplane to be is parked, but that's not why we have them," he said. "It's a very old fleet. What really should impress you is that the team can keep it going, when I think this challenge would have crushed any other Air Force. ... It was difficult, [but] we saved American lives."
Ray said that Air Force Chief of Staff Gen. Charles "CQ" Brown has taken significant steps to balance how the service uses its aircraft by better prioritizing missions.
"We can do anything; we just can't do everything," Ray said.
But the military's continual need for surveillance in the Middle East led the Air Force to make trade-offs on modernization that might not be what's necessary in a war against a major power, Carlisle said.
With the U.S. military's primary foes in the late 2000s being the Taliban and Iraqi insurgents, he said, there was little need for an advanced fighter with stealth capability -- but a tremendous need for drones that could linger over areas and either watch or strike.
"Every corner of the Iraq and Afghanistan and Syria campaign wanted a Reaper overhead to give him the ... 'unblinking eye,'" said Carlisle, who after retiring became president and CEO of the National Defense Industrial Association, which counts defense contractors among its members and describes itself as a nonprofit group looking to educate the public on aspects of national security.
So in 2011, the F-22 Raptor fighter was canceled, with only 186 of the originally proposed 750 stealth aircraft now in the fleet. Meanwhile, the Air Force set a punishing pace for airmen to fly MQ-1 Predator and MQ-9 Reaper drones, which in 2015 briefly hit a high of 65 combat air patrols per day -- a crushing operations tempo, and a significant investment in resources and manpower.
That balancing act made sense at the time but might not pay off in a war against China, Carlisle said. The Predators are now retired, and Reapers -- though capable drones -- would be slow and easy pickings for Chinese radar and anti-aircraft systems. Meanwhile, an F-22 restart is not in the cards.
A Second Chance in a Long War
After Hendrickson nearly lost his leg, he made jokes about being a pirate with a peg leg the following Halloween. But underneath, he was wracked with guilt and feelings that he had let his brothers in arms down by not being there anymore. The chances of him walking unassisted again were against him, let alone serving as a Green Beret in combat. He began replaying in his mind his steps before the explosion, Monday-morning quarterbacking, and filled up with self-directed anger.
On the ninth anniversary of 9/11, Hendrickson and his unit launched a mission to clear the Chutu Valley in Uruzgan province, along the Helmand River. Early on the next day, as the sky began to lighten, his team moved toward its first set of compounds, which were known to be used by the Taliban.
The team's interpreter had exposed himself to danger, so Hendrickson went over to the compound to pull him back. Something moved fast and caught Hendrickson's eye -- he wasn't sure if it was an animal or a person running -- and he took a step forward in the entryway to see what it was.
His right foot stepped on a pressure plate, and the IED detonated.
He didn't feel anything -- not at first. He hit the ground and couldn't figure out what had happened. The dust and ammonia from the explosive swirled and made it impossible to breathe. If he didn't stand up and get out of there, he thought, he would suffocate to death.
"My brief time on an ODA [Special Forces Operational Detachment Alpha] was cut short because I decided to peek around that corner, like an idiot," Hendrickson said. "Then rage sets in -- 'I'm so stupid, why did I do that.'"
Depression set in, and at times, thoughts of suicide even crossed his mind.
But he pushed through his depression, and spent all of 2011 rehabilitating, motivated in part by his memory of the Taliban celebrating, and a question his dad asked him: When he is an old man and looks back, will he be ashamed because he allowed the injury to define him? Or will he be proud because he used the challenge to make himself stronger?
He returned to Afghanistan alongside his fellow Green Berets -- with his leg in his IDEO brace -- in March 2012. On another deployment in February 2016, he rallied his team and fought back against a heavy Taliban ambush in Baghlan Province, through machine-gun, rocket-propelled grenade, sniper and mortar fire, ultimately receiving the Silver Star for his bravery.
Hendrickson first joined the Navy four years before 9/11. He deployed to the Persian Gulf, and later moved to the Air Force and deployed to Iraq. He finally transferred to the Army, became a Green Beret, and deployed to Afghanistan for the first time with the Seventh Special Forces Group in May 2010, during the surge. He continued with deployments to Afghanistan after nearly losing his leg, with the war still going while he rehabbed, and he wore the uniform until January 2020. In his more than 22 years of service, 18 came during years of war.
Like many service members, Hendrickson doesn't describe his combat experience, or even his injury, in terms of shock. They're points that are part of his long history serving in the military, the sorts of experiences that could be recounted by numerous other service members forged in a generation of combat.
They're the new normal.
And Hendrickson views even the near-loss of a limb as having a silver lining.
"Getting blown up was one of the best things that's happened to me," he said. "I used it [the leg situation] to my benefit. Yeah, I got some cool scars and whatnot. But I've become a better man because of the situation I went through."