Story highlights Women had not been allowed to participate in certain military roles last year

The women joining the Marines as infantry graduated from the the School of Infantry

Washington (CNN) An infantry battalion at Camp Lejeune in North Carolina received three historic additions Thursday -- the first women infantry Marines.

The three women will serve in the 1st Battalion, 8th Marine Regiment, with specializations as rifleman, machine gun and mortar, according to 1st Lt. John McCombs, a Marines spokesman.

The identities of the women are not being released at this time to allow them to get acclimated to their unit, McCombs said. The unit already has three females in leadership roles and they will be able to help with the transition, he noted.

Women had not been allowed to participate in certain military roles until Defense Secretary Ash Carter announced that starting in January 2016, the military would be required to open all combat positions to both males and females.

Women have been working to fight alongside men for more than 150 years, according to the US military -- going as far back as the Civil War where more than 400 women disguised themselves as men.

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