Josh's rank is honorary but earned over a tough day of drills. The 15-year-old rode in tanks, learned about rifles, tried out Army chow and listened to tales of leadership last week.
The day in uniform may be the only one he gets.
Josh has a type of brain tumor that's usually fatal. While other kids in his shoes take trips to Disneyland, Josh asked the Make-A-Wish Foundation to make him a soldier.
"I'm having so much fun," he said after touring an M-1 Abrams tank.
Josh was adopted for the day by troops of Fort Carson's 3rd Brigade Combat Team who squired him about the post, loading him up with a career's worth of honors and experiences in one day.
He started off as a private in the morning and got promoted at every stop. He was made a cavalryman, a Ranger, a tank master gunner, a pilot and an MP.
Josh knows too much about battle already. He had a seizure in July, and doctors discovered a tumor the size of a tennis ball inside his head. He has faced surgeries, radiation and chemotherapy.
Doctors say he has done amazingly well.
"Usually, in adults, it's considered terminal," said his mother, Debbie.
To come to Fort Carson meant a day's break from treatment at Children's Hospital of Colorado in Aurora.
Like any new recruit, Josh started with a new uniform. By the end of the day, he was wearing far more decorations and patches than are allowed by regulation. He was allowed to proceed to the top enlisted rank anyway.
"The whole Fort Carson community pitched in," said Capt. Shaun Manley, a 3rd Brigade spokesman. "Everyone wanted to help."
Seeing a young man facing tough odds showing so much awe and wonder at their work was tear-inducing for some soldiers.
"It definitely makes us proud," Staff Sgt. Bradley Thieroff said.
Lt. Col. Jason Sabat, who commands the brigade's 1st battalion of the 8th Infantry Regiment, said his troops jumped at the chance to help Josh.
"It's truly humbling," he said.
Josh's dad, Tony, said it was just good to see the teenager smile.
"He's so happy; he doesn't know which way to look," he said.
Josh finished the day on a tank, roaring out to a range for drills.
The young man's battle is continuing. For the next year, he'll undergo increasing doses of chemotherapy. To learn more about his fight, visit www.team-josh.com.
Sgt. 1st Class Derrick Kolenda said Josh showed his troops a thing or two about toughness.
"The fact that he wanted to be one of us for a day is just an honor," Kolenda said.