EGLIN AIR FORCE BASE, Fla. — Air National Guard C-130s roared over the lush, shaggy grass of the Elizabeth Drop Zone here last week, a near-steady hum overhead. Army Ranger students were a few hours into a mission known as Operation Pegasus, and needed to parachute in from a height of about 1,100 feet.

Eventually, the students’ green chutes dotted the early-evening Thursday sky, floating down into the open fields of Eglin with 70 pounds of equipment, food and water before disappearing into thick brush, beginning a 10-day exercise that ends this Saturday and is the last major field event in the Army’s famously difficult Ranger School.

History is in the balance: For the first time, two female students advanced to the third and final phase of the exhausting course in the swamps of Florida, and are within reach of graduating. If they pass, they will become the first Ranger-qualified women celebrated at an Aug. 21 graduation at Fort Benning, Georgia.

If they graduate, the Army must confront a separate, but related decision: Whether to allow women to try out for the elite 75th Ranger Regiment. The highly trained Special Operations unit carries out raids and other difficult missions and includes about 3,600 soldiers. It remains completely closed to women, even though some of the jobs in it, ranging from parachute rigger to intelligence analyst, are open in other parts of the Army.

As part of the military’s ongoing assessment of how to integrate women into combat roles, women were allowed into Ranger School this year. Thus far, the Army has said that any woman who graduates will be allowed to wear the prestigious Ranger Tab, but won’t be allowed to serve in the Ranger Regiment. The decoration is considered a necessity to advance in many Army careers.

Other elite forces, including the Navy SEALs and Marine Corps Forces Special Operations Command, also are grappling with whether they will incorporate more women in the future, and how. If the services want to keep any position closed, they must seek an exception to the new policy from the Pentagon.

Critics of integrating the military’s most elite units with women have so far been able to say that no woman has demonstrated she can keep up with men by passing Ranger School, a physical and mental crucible that includes phases at Fort Benning, on the mountains of northern Georgia and in the coastal Florida Panhandle swamps. A woman completing the course would weaken the argument against gender integration in the military.

The Army allowed a few journalists to observe three days of Ranger School at Eglin last week, an effort to demystify how it is evaluating soldiers and to underscore that the female students are being treated no differently than the men.

Col. David Fivecoat, commander of the Airborne and Ranger Training Brigade that oversees the school, recalled leading an infantry battalion with the 101st Airborne Division in Afghanistan in 2010 and 2011, and sending at least two female soldiers to virtually all of his bases.

“I wanted that capability in country, and this to me seems like a logical step,” he said. “Why wouldn’t you want that woman that you’re going to put out there to provide that capability to be Ranger-trained?”