He had to take it.

He was a combat veteran who had simply seen too much -- too many brother Marines dead on the battlefield in Iraq. When he came home he faced fresh battles: alcohol, arrests and a suicide attempt.

He chose a date that resonated -- and on September 11, 2015, Jonathan Hancock set out to prove that hurt would no longer define him.

Carrying 70 pounds of gear, he hit the road to walk 5,800 miles from Maryland to California and many backroads in between. He was searching for hope and healing.

"On a cross-country journey like this, you pitch a tent when you can," Hancock told CNN's John Vause. "I gotta be honest, there's some trespassing along the way, so you have to keep a low profile. I did pick up a hotel a couple times month to shower and clean up a bit."

Snakebites and poison oak

Along the way, he got poison oak in California, impetigo in Georgia and snake bites in South Dakota and Louisiana.

Hancock was forced to climb a tree in Montana to avoid a moose, ran into a white wolf in the Big Horn Mountains in Wyoming and was stalked by a mountain lion for three days in Oregon.

"That really sucks when you can see it follow you down the road," he said.

He endured all of this for three reasons, he said. He did it for self-healing, to visit fellow Marines and Gold Star families of the fallen -- and to spread awareness about what it's like for a war fighter to come home.

Iraq combat veteran Jonathan Hancock faced long spells alone on his 5,800-mile walk from Maryland to California.

"I had to lay myself on the altar of humility," Hancock said. "I wanted to show my brothers that it's okay to feel those feelings of darkness. And it's really okay to talk about them. That's such a higher purpose and transcends more than just my unit."

Hancock fought with the 2nd Battalion, 4th Marine Regiment -- nicknamed The Magnificent Bastards -- in the first Battle of Ramadi in 2004.

The unit suffered the highest casualty rate in the Iraq War out of any single infantry battalion with 20% of the entire 1,000-man force killed or wounded, according to the U.S. Marine Corps. For many the battle hasn't ended. Hancock's marathon trek to honor their continuing struggle now is being turned into a documentary called "Bastard's Road."

Healing deep wounds

Hancock says 25-30% of his unit endures post-traumatic stress disorder and at least seven have committed suicide. "Not a man from Ramadi comes home and doesn't feel something," he said.

Hancock hopes his walk and his brotherhood can help heal some very deep wounds.

"There's been tears and there's been lots of hugs and reassurances that we're gonna be there for each other," Hancock said. "You speak about bad things and the memories that you hold dear to yourself and things you don't share with your families. So you share them with each other."

Hancock also knocked on the doors of Gold Star families.

"Their sons never came home and so to see a man who knew their sons or knew of their sons," Hancock said, "I imagine that they would see their son walking home. It was tough for them and it was tough for me because you have to share in that emotion and grief.

"I wondered if I was strong enough to take that feeling on -- over the course of time, I realized that I was and I should continue to do this."

Now, almost 6,000 miles later, with feet that look like a "prehistoric river bed," Hancock's walk is nearing an end. On December 12, he'll walk into Camp Pendleton in southern California. This time he'll be far from alone. Many brothers in arms from his old battalion will be there to guide him through the gates.

They'll do so knowing that the United States is again in combat in Iraq. American troops are helping Iraqi coalition forces battle ISIS to recapture cities Hancock and his comrades fought for more than a decade ago.