Will Snow grew up in Foxborough and moved to California in his 20s. His sister Courtney was 16 when she was diagnosed with cancer. She went into remission, but when she was 21 the cancer came back with a vengeance and Will Snow came back from California with a purpose, to be with his sister at Massachusetts General Hospital.

“It was in her knee, and then it went into her spine,’’ he said. “I stayed with her for eight months. I never felt more helpless. Just sitting there. I couldn’t help her. I couldn’t help anybody. She’d get a roommate and the roommate wouldn’t make it through the night.’’

When his sister died, Will Snow knew he had to do something, anything, that would allow him to do something, anything, to help others. He thought about medical school but didn’t have the money.

Then he thought of the Army. But not just the Army. He wanted to be a Ranger.

He had watched documentaries and movies about the 2nd Ranger Battalion scaling the cliffs on D-Day up to Pointe du Hoc, with gunfire raining down on them, and said to himself, “I want to be one of them.’’ More specifically, he wanted to be a medic.

“I was 25 at the time,’’ he said. “Felt a bit old for the infantry. But I wanted to be with those guys.’’

He wanted to go to war and not feel that sense of helplessness he felt in his sister’s room at Mass. General.

He enlisted in 2005 and after basic training, he came home and married his sweetheart, Amber, before getting his Ranger tab and joining the 2nd Ranger Battalion at Fort Lewis in Washington.

“It wasn’t a big wedding,’’ he says. “It was in a coffee shop in Rhode Island. We just wanted to get married before.’’

Before his first deployment to Iraq. Because you never know.

The first deployment, near Balad, north of Baghdad, went well. Or as well as those things can go.

So did the second deployment. But in a war that required far too much of far too few, Will Snow went back to Iraq for a third time, in 2010, and it was not the charm.

The Stryker armored vehicle he was riding in tumbled down a 20-foot embankment into a canal, and he and the other soldiers inside were tossed around like pinballs. The butt end of an AK-47 carried by an Iraqi soldier knocked him out.

“I remember laying there, and I couldn’t get up. One of the dude’s AKs was right in front of my face. I was pinned, looking down the barrel of that AK and I’m thinking, ‘If this is how I go, my wife’s going to be really mad.’ ’’

He’d hurt his head, his back, his neck, but, like all medics, all he cared about were his soldiers.

“I just thought it was a concussion,’’ he said. “I’d had them before, playing sports, so I just shrugged it off, walked it off.’’

He sucked it up for the month he still had left before returning stateside for the birth of his first child, a daughter he and Amber named Teagan.

Amber noticed first.

“He was angry, and that’s not Will,’’ she said. “The guy who went to Iraq was not the guy who came home.’’

Will’s head was pounding. It was unbearable, disorienting.

“I don’t remember my daughter being born,’’ he said. “I don’t remember the first year. I’d empty the dishwasher and put everything in the wrong place. I’d walk into a room and just stand there, not knowing why I was there.’’

Back at Fort Lewis, they kept running tests and telling Will Snow there was nothing wrong with him. But the headaches, the panic attacks, the disorientation told him and Amber otherwise. He had a traumatic brain injury and post-traumatic stress.

They moved to Yuma, Ariz., and there was even less treatment available. After his discharge from the Army, Will found it impossible to navigate an overwhelmed Veterans Administration.

Amber was sitting there in Arizona four years ago, watching a Red Sox game on TV, when a segment about Home Base came on. It was the first she had heard of a clinical program run by the Red Sox (whose principal owner also owns the Globe) and Massachusetts General Hospital that treats the invisible wounds of war like TBI and post-traumatic stress.

Not long after, they moved back to Massachusetts and Amber resolved to take part in the annual Run to Home Base, a race that ends with military members and their friends and families crossing home plate at Fenway Park.

Amber ran in the race again last year, and handed the phone to Will one day and said, “You have to talk to them.’’ A clinician at Home Base scheduled an appointment, the same kind of appointment that Will couldn’t get at the VA.

“I have empathy for the VA, seeing how overworked some of the people are. They couldn’t help me. Home Base did. It’s cutting edge. It worked for me.’’

On Saturday, Amber and Will Snow were back at Fenway Park. Amber ran, for a third time, while Will looked after Teagen and her little sister Addie.

“I got him back,’’ Amber Snow explained. “It took a while, but I got my husband back.’’

As the two major political parties in this country pat themselves on the back at their respective conventions, saying far too little about what they would do to help veterans who continue to kill themselves at a rate of 20 a day, the long road that Amber and Will Snow are still on reminds us there is still plenty to do for the soldiers, sailors, airmen, and Marines who left a bit of themselves back in Iraq and Afghanistan.

“There’s still too much stigma about seeking out help, but it’s lessening,’’ Will Snow said. “I’ve been on the phone, talking to buddies all over the country, telling them that Home Base will fly them here for treatment in Boston. I’m trying to get the word out.’’

Will Snow won’t rest until everybody he served with knows there’s help here in Boston if they need it. It’s like that old Army saying: Rangers lead the way.

Kevin Cullen is a Globe columnist. He can be reached at cullen@globe.com. Follow him on Twitter @GlobeCullen.