Fort Carson's mounted color guard was missing something.

Until last year, the military base was mule-less. And there are few life forms tougher than an Army mule.

After a long search and months of training, a matching pair of half-brother mules elicited cheers from at least 4,000 rodeo fans at the opening night of Pikes Peak or Bust Rodeo Wednesday.

Sgt. Nathaniel Aston joined Fort Carson in 2011 primarily to train and care for a pair of matching mules, same in color and size. The search was over in April 2012, when Colorado Thirty Group donated John and Henry. In January, the mules won first place at the grand-daddy of them all - the National Western Stock Show in Denver.

"Henry's fatter," Sgt. Josh Keltner, operations sergeant for the Fort Carson mounted color guard, said. "He always has been."

The color guard exists primarily to preserve army history, Aston said, and the mules contribute to that end. They pull a ceremonial 1878 wagon at parades and rodeos.

Crowds recognize the traditional wagon, Keltner said, and elderly people especially enjoy the mules' show.

"There's a certain poetry about the old west that these guys bring back a little bit," Keltner said.

Only a handful of the color guard's 15 servicemen work with the mules. Aston said the job requires a calm demeanor, something many of his peers do not have.

"We found that keeping on a conversation with them, even though they can't talk back, keeps them calm and keeps me calm," Aston said. He often tells John and Henry to, "Do what you guys know you have to do," he said.

Specialist Nicole Boughan drove the mules with Sgt. Joshua Moya in shotgun Wednesday. The small team rotates drivers.

"For 18 months of two years, our only duty is taking care of these mules and carrying the colors," Aston said.

The mules riled the crowd mid-rodeo, following young mutton busters.

"I hope it makes them proud of everything the army's done," Aston said.