Through the darkness, the soldiers pushed forward toward their objective. Sweat was dripping off the chins of some, hitting the ground as each mile passed.

Their rucksacks seemed heavier with each passing step, their helmets weighing down like lead covers on their heads. They had to complete a full 12 miles before their trek was done.

Once they reached their destination, there was one more task at hand: each soldier had to treat a simulated casualty and carry him out on a litter.

This was the final event for the Expert Infantryman Badge testing that took place Dec. 11-15, 2017, at Joint Base Lewis-McChord.

Out of the 324 1-2 Stryker Brigade Combat Team soldiers who started the EIB testing, only 73 successfully completed all the required tasks and earned their badge -- making the attrition rate 78 percent.

"The test has evolved over the years," said Command Sgt. Maj. Walter A. Tagalicud, the I Corps command sergeant major. "It certainly differs from the one I participated in to earn my EIB in 1989. But, the spirit and intent remain. There is no greater individual training mechanism to building the fundamental warrior skills required in our profession, than the EIB."

There is a lot of train up to the EIB, said Spc. Tyler Conner, an infantryman with Company A, 2nd Battalion, 3rd Infantry Regiment. Even if a soldier is not trying out for the EIB, the train up for the testing is valuable to see the right way of doing infantry tasks. When a soldier finally earns the EIB, it shows that they have honed their skills enough to be called an expert infantryman.

The EIB evaluation included an Army Physical Fitness Test, with a minimum score of 80 points in each event; day and night land navigation; medical, patrol, and weapons lanes; a 12-mile forced march, and Objective Bull (evaluate, apply a tourniquet to and transport a casualty).

"These crucial skills are the building blocks to our battle drills and collective gates," Tagalicud said. "The Expert Infantryman Badge is as much about the training, leading up to and through the testing, as it is about proving your mettle."

"Earning the EIB was one of the best experiences I had in the Army," said Sgt. Wilmar Belilla Lopez, a soldier with 2-3 Inf. "Being tactically and technically proficient is the core of being a soldier. When a soldier earns their EIB, it signifies they have achieved a level of proficiency all soldiers should strive for."

"The Greek Philosopher Heraclitus said, ‘Out of every 100 men, 10 shouldn't even be there, 80 are just targets, nine are the real fighters and we are lucky to have them -- for they make the battle. But the one, one is a warrior, and he will bring the others back,' Tagalicud said while addressing the new EIB holders.

"You are that warrior. You infantrymen, you soldiers, you leaders and candidates are the one in a hundred," he said. "Many stepped forward to answer the question ‘am I good enough?' For you, the answer is a resounding yes!"

The EIB was developed in 1944 to represent the infantry's tough, hard-hitting role in combat and symbolize proficiency in infantry craft.

For the first EIB evaluation, 100 noncommissioned officers were selected to undergo three days of testing. When the testing was over, 10 NCOs remained. The remaining 10 were interviewed to determine the first Expert Infantryman.

On March 29, 1944, Tech. Sgt. Walter Bull was the first soldier to be awarded the EIB.

The Army is terminating the use of temporary early retirement authority, or TERA, for soldiers with less than 20, but at least 15 years of service.

"Since 2012, temporary early retirement authority has served as an effective tool for drawing down the Army's end strength," said Secretary of the Army Mark T. Esper, in a memorandum released Dec. 15. "However, the National Defense Authorization Act for fiscal year 2017 increased Army end strength and we have ceased the drawdown."

With the drawdown ended, the Army has put in place a process to end the use of TERA earlier than originally planned, in a way to ensure a smooth transition, said Hank Minitrez, with the Army's Office of the Deputy Chief of Staff, G-1.

Soldiers eligible for TERA must submit a request through their chain of command no later than Jan. 15. Commanders are required to expedite the applications, as the authority to approve TERA requests will expire Feb. 28.

One exception is for soldiers whose results from the fiscal 2017 promotion selection board will not be released until after Jan 15. They must submit a TERA request no later than 30 calendar days from the release of the board results. Once the request is received, authorities will have 45 calendar days to approve or deny the soldier's request.

Results from four fiscal 2017 officer boards have not yet been released, Minitrez said.

Along with ending TERA, the secretary's memo also terminated temporary changes to the minimum years of active commissioned service soldiers must have to retire as an officer. Since 2014, soldiers have needed only eight years commissioned service to retire as an officer, and now that minimum goes back to 10 years commissioned service (with a total of 20 years active federal service.)

Soldiers approved for TERA must retire no later than Sept. 1. Any changes in the effective date of retirement beyond Sept. 1 are not authorized, according to the memo.

For some animals, such as salamanders, regrowing a missing limb is a common healing process. But what if people could do the same? Could the future of treating amputations include soldiers regrowing their own muscle, bone, and nerve tissues?

"We're not quite there yet," said Army Lt. Col. David Saunders, extremity repair product manager for the U.S. Army Medical Materiel Development Activity, Fort Detrick, Maryland. "What we're trying to do is develop a toolkit for our trauma and reconstructive surgeons out of various regenerative medicine products as they emerge to improve long-term outcomes in function and form of injured extremities."

Saunders was part of a session focusing on the research being done on extremity regeneration, part of a larger theme of regenerative medicine at the Military Health System Research Symposium. Saunders said that while there's been amazing progress in the areas of using synthetic grafts to start the regrowth of muscle, nerve, vascular, and connective tissues, it's still not the same as the real thing. "We would like it to be as restorative as possible, resist infection ... and be durable," he said. "This is going to be implanted in young people who may go on to live another 60 to 70 years."

One researcher is using fillers to bridge the gap in damaged bones, hoping to figuratively bridge the gap between current regenerative techniques and the ideal: people regrowing lost limbs. Stephanie Shiels with the U.S. Army Institute of Surgical Research, Fort Sam Houston, Texas, talked about her research to develop a synthetic bone gap filler that heals bones and reduces infection by infusing those grafts with a variety of anti-microbials.

"We know that it reduces infection," said Shiels. "Other things to consider include adding a bulking agent ... to help regenerate bone."

Other research focuses on regrowing muscle lost in traumatic injuries, as well as recovering nerves, or at least preserving them, for future use. But besides treating those deep tissue wounds, there's something a bit more on the surface that can impact troops: skin. The skin is known for its regenerative properties. Research is being conducted to help it do that job better and recover scar tissue.

Jason Brant with the University of Florida has turned to a mouse to help the military reduce scarring of injured soldiers. He said the African spiny mouse has evolved a capability to lose large parts of its skin when a predator tries to grab it, allowing the mouse to escape and live to recover. The mouse is able to recover scar-free in a relatively short amount of time, which is remarkable considering the amount and depth of tissue lost. Brant wants to know how the mouse is able to do that.

"Warfighters and civilians alike suffer large surface (cuts) and burns, and these result in medically and cosmetically problematic scars," said Brant. "The impacts of these scars ... are really staggering. The ability to develop effective therapies will have an enormous impact not only on the healthcare system but on the individuals as well."

He believes a certain protein in the mouse could be the key, but he's still trying to figure out how it could apply to humans.

Another way to reduce scarring involves the initial treating of wounds. Army Maj. Samuel Tahk, a research fellow with the Uniformed Services Health Consortium, passed around to attendees samples of biocompatible sponges he's investigating for their ability to promote skin healing, and thus, reduce scarring.

"It provides a scaffold to start regenerative growth," said Tahk. "This could simplify patient care and also reduce costs."

While the field of regenerating body parts is still new, Saunders believes it will be the future of wounded warrior care.

"Extremity wounds are increasingly survivable due to the implementation of body armor and damage control surgeries," he said. "(There are) many wonderful things emerging in the field of regenerative medicine to restore form and function to our wounded warfighters."