"File in and no one talk to anyone," booms the cadre.

About 50 soldiers huddle into a tent deep into the ranges at Joint Base McGuire Dix-Lakehurst, as the canvas walls shudder from unrelenting winds. The sounds of rhythmic blasts from other sites go off in the background but no one takes notice. Every soldier stays laser-focused on the instructions ahead for their land navigation portion of the Expert Field Medical Badge (EFMB).

The EFMB is one of the most coveted badges in military medicine. Candidates must pass a written test, a series of training lanes where they are tested on combat care and other military survival skills, perform day and night land navigation, and complete a 12-mile road march.

Most who have gone through it will say land navigation is the toughest part. One missed point is the end of the exercise and a ticket home.

Master Sgt. John Castillo, a lane leader from the U.S. Army Public Health Command, Aberdeen Proving Ground, Md., said it was the land navigation that knocked him out of the ranks the first time he tried to get the badge.

"You know I was a first sergeant -- a leader of soldiers -- and when it happened. I did not want to talk to anybody. But when I returned to my unit, the sergeant major came to me, offered tips and said the next time you go, you'll get it. He really helped me out," said Castillo.

In 2012, Castillo achieved his goal at Joint Base McGuire Dix-Lakehurst, the first time the base ever held an EFMB competition.

Sgt. 1st Class Royregus Cosby, a member of the cadre who is regularly assigned to the 6th Medical Logistics and Management Center, added that the achievement is more than a "chest mount."

Cosby said, "If you see a medic coming up to you in combat and they have that badge, you know that you are getting the best."