This period is commonly known as RAP week, with RAP standing for Ranger Assessment Phase.

During those four days, the soldiers were evaluated on a series of punishing physical events. They had to conduct a physical fitness test consisting of 49 push-ups, 59 sit-ups, six chin-ups and a five-mile run in under 40 minutes.

They also underwent a swim test and a land navigation test. The soldiers also had to complete a 12-mile foot march wearing a 35-pound rucksack in under three hours.

A total of 19 female and 381 male soldiers started the two-month Ranger School on Monday.

Three women and 78 men were eliminated from training after the PT test on the first day.

U.S. Army Soldiers conduct the Darby Mile buddy run and an obstacle course during the Ranger Course on Fort Benning, Ga., April 21, 2015. Soldiers attend Ranger school to learn additional leadership and small unit technical and tactical skills in a physically and mentally demanding combat simulated environment. (U.S. Army photo by Pfc Antonio Lewis/Not Released)
U.S. Army Soldiers conduct the Darby Mile buddy run and an obstacle course during the Ranger Course on Fort Benning, Ga., April 21, 2015. Soldiers attend Ranger school to learn additional leadership and small unit technical and tactical skills in a physically and mentally demanding combat simulated environment. (U.S. Army photo by Pfc Antonio Lewis/Not Released)

Soldiers conduct the Darby Mile buddy run and an obstacle course during the Ranger course on Fort Benning, Georgia, April 21.

Photo Credit: Pfc. Lewis, Antonio/Army

After RAP week, eight women and 184 men remained in training – this represents an overall success rate of 48 percent, according to the statement from Fort Benning.

There was a 42.1 percent success rate for the female soldiers and a 48.3 percent success rate for the male students, according to Fort Benning.

Officials said these numbers are "within historic norms for the Ranger course."

The training that began Monday is a one-time, integrated assessment at the Army's famously punishing Ranger School.

The assessment is part of a wider effort to determine whether and how to open combat arms jobs to women, and it is a first for Ranger School, which until now has been open only to men.

On average, about 45 percent of Ranger School students will graduate. As many as 60 percent of all Ranger School failures will occur in the first four days of during the Ranger Assessment Phase, commonly known as RAP week.

In fiscal 2014, PT test failures made up the largest number of Ranger School failures.

Twenty women qualified to attend the integrated Ranger School assessment after successfully completing the Army National Guard Ranger Training Assessment Course.

To prepare for the April assessment, the Army required female candidates to attend the two-week RTAC, setting aside seats for female candidates in each iteration of the course between January and April.

RTAC has historically been a strong indicator of whether a candidate will be successful at Ranger School. Data has shown that more than half of the soldiers who complete RTAC will successfully complete Ranger School.

Women who successfully complete Ranger School will receive a certificate and be awarded the coveted Ranger tab. They will not, however, be assigned to the 75th Ranger Regiment, which is separate from Ranger School.