Inside Ranger School: What the First Female Graduates Had to Beat

— -- After nearly four months of grueling training, two female soldiers will make history as the first to graduate the Army’s elite Ranger School.

While the Ranger Course is spread out over three phases in 62 days, the two female students were recycled back through two of the phases. Approximately 34 percent of students who enter Ranger School recycle at least one phase of the course, according to the Army.

Starting in April, ABC News was given an inside look at the high-stress and high-stakes environment that tests the Army’s top combat leaders.

THE DARBY PHASE

“Ranger school is the absolute toughest, most demanding course in the military. Not just in the Army, I think actually in the military,” Command Sgt. Major Curtis H. Arnold Jr. told ABC News as he oversaw the first phase of Ranger School at Fort Benning in Georgia. “We tax you mentally, physically and emotionally.”

Behind him, candidates were in the midst of the 21-day phase designed to stress stamina through intense field training. As part of a fitness assessment course, the students must complete a land navigation test, run an obstacle course, and hike a 12-mile road march with a 47-pound backpack in under three hours.

Students are then assessed by a Ranger instructor in a patrol course involving demolitions tests, field craft, and battle and ambush drills before they meet approval for the Mountain Phase.

THE MOUNTAIN PHASE

Located in the northern Georgia mountains, the Mountain Phase is designed to exhaust the students through training under mental, physical fatigue with rugged terrain, little food and even less sleep.

In addition to a knot test, four days are spent on military mountaineering, including a full day of climbing and rappelling over high-angle terrain with heavy equipment.

The soldiers then push through ten days of patrolling both day and night before being “deployed” to their final phase.

THE SWAMP PHASE

The Swamp Phase brings the remaining, exhausted candidates to the severe-weather prone Camp Rudder in the Florida panhandle.

According to an Army document, 22 students have died over the years during the 18-day swamp course, which puts a large focus on combat scenarios, both air and waterborne.

That same document may need correction, though, as it states, “Training remains tough for the men who aspire to be the Army’s most elite warriors.”

Those same elite warriors will add two women and 94 men to their ranks in a graduation ceremony this Friday.

ABC News' Tom Thornton contributed to this piece.