"It was great!" Mason tells PEOPLE. "I loved it!"
Mason has been fighting pilocytic astrocytoma, a rare form of tumor, since he was 18 months old, his parents Mark and Laura Giove tell PEOPLE. The tumor grows in odd directions, and is located so deeply within Mason's brain that it cannot be removed surgically.
Mason relies on a feeding tube for sustenance. He struggles to communicate. His muscles are weak.
"He doesn't get to do a whole lot," says Mark. "He has a wheelchair. He can't play sports."
The only way to fight the tumor is with chemotherapy that threatens Mason's eyes, bones, heart, and other organs. The treatment makes him violently ill.
Neither the tumor nor the chemotherapy, however, dampens Mason's inquisitive mind.
"He loves the Army," Mark says. "He loves watching movies about D-Day, and learning about military history. And he really, really loves tanks."
Patrick A. Albright / Fort Benning
Which is what lead to Mason become an armor commander at Fort Benning.
The process began last fall, when longtime family friend Eric Runci, who lives near Fort Benning, visited the Giove family near Boston.
"Mason is the friendliest kid ever," Runci tells PEOPLE. "He'll just come right over to you and start talking. He was telling me all this stuff about tanks. You could see how much he loves them."
The exchange gave Runci an idea.
"If this makes him happy, let's show him some real tanks," Runci says. "Let's make him feel like a kid."
"Detachment Mason" swung into action.
Runci contacted his friend Andrew Kloster, who works at Fort Benning and knows Lt. Col. Jeffrey Paine, who commands an armored cavalry (tank) squadron on post. One thing led to another, and the mission – to appoint Mason a tank commander for a day – was approved.
Runci and his wife Megan held a fundraiser, selling homemade reindeer cork ornaments, in order to finance the trip. Soon Mason and Mark were headed to Columbus, Georgia, where the post is located.
At Fort Benning, Mason was commissioned into the 16th U.S. Cavalry Regiment, at the rank of brigadier general. The soldiers there issued Mason his own uniform. It fit perfectly. The soldiers formed a convoy to escort Mason and Mark into the field.
"We drove for 45 minutes," Mark says. "Suddenly in the middle of the woods, we go to the top of a hill, and there were all these tanks. Just there. Not doing anything. Just there."
Patrick A. Albright / Fort Benning
"There's this giant M1, coming up the road," Mark says.
The Abrams M1A2 Main Battle Tank rolled to a halt in front of its new commander, Mason. The soldiers helped lift Mason up and into the vehicle.
"He climbed all over it," says Mark.
The soldiers showed Mason a Bradley A3 fighting vehicle, and fired off six rounds from another tank. The soldiers then brought Mason into a training simulator, where he hot-rodded his tank at high speed.
"That was fun!" says Mason.
But if Mason was happy, the soldiers were moved by the small boy and his big fight. One by one, soldiers presented the young general with deeply personal gifts.
One man gave Mason his own dress uniform, complete with medals. Another gave Mason his silver Cavalry spurs, saying, "I don't want you ever to give up. If you ever have that feeling, hold these spurs, and don't ever give up."
"That was nice of them," Mason says.
"All Mason has known his whole life is, fighting this tumor," Mark adds. "To get his mind off his illness was a wonderful thing they did for him. I was bawling like a baby."
"We wanted nothing more than to make this day one he and his father would never forget," says Captain Bryce Land, the A Troop commander who helped arrange the visit. "Mason's ever growing smile made every bit of effort completely worth it."
"Being able to do this was the highlight of my career," says Staff Sergeant Dennis Mathews, who draped his own uniform around Mason's shoulders. "I've watched things like this on TV before and thought it was awesome. To be a part of it, to see it first hand was amazing."
Word of Mason's fight against the tumor spread through the military community. When Mason returned home, active duty military and veterans around the world began sending morale boosters to help cheer Mason as he goes through his latest round of chemotherapy.
Among other items, supporters have sent a flag from a combat outpost in Afghanistan; a cap from the USS Missouri at Pearl Harbor, Hawaii; coins from an Air Force Special Tactics squadron on Okinawa, Japan and patches from the shadowy Joint Special Operations Command at Fort Bragg, North Carolina.
"It really makes him smile," says Mason's mom, Laura. "It sounds like a small thing, but to him, it's huge. Every day it seems like something new is on the way. It's been so wonderful."
The ongoing support from "Detachment Mason" comes at the right time. The Giove family recently learned that Mason's tumor has grown.
"The chemo needs more time to work," Laura says. "We're letting the treatment take its course."
Mason stays focused on his interest in the military.
"My tanks are great!" Mason says. "I want to go back!"