Fort Bragg in North Carolina conducted a cyber-attack military exercise for 12 hours overnight Wednesday into Thursday morning that simulated how personnel would respond to an attack that crippled the base's power supply, reported The Charlotte Observer. And according to several Facebook post from base officials, the exercise was an unannounced military exercise.

Fort Bragg is the biggest military installation in the world with more than 50,000 active duty personnel. Base officials said the purpose of the drill was to "to identify shortcomings in our infrastructure, operations and security" in a rolling blackout.

"We spoke to the Fort Bragg Operations Center and they confirmed there are outages throughout the post...Obviously no one knows when the power will come back on. We’ll post more as we find out," said a post on Fort Bragg's Facebook page just as the power was intentionally shut off around 10:00 to 10:30 PM Wednseday.

At 4:30 AM Wednseday, another Facebook post said, "As many of you know Fort Bragg is facing a blackout at this time, but the post is open."

Base officials said the blackout is widespread, affecting everything from traffic signals to restaurants on the base. No explanation was communicated to personnel, along with a fabricated story of how base officials were ignorant about the situation, even telling soldiers that they were trying to "sort this out and get a clearer picture of what is going on."

Warnings across the base were issued: "Driving in Fort Bragg is extremely hazardous at this time especially at the intersections so use caution when approaching them. If you observe any suspicious activity call 911,” base officials said in a 5 AM Facebook update.

At 6:13 AM, Womack Army Medical Center in the base announced that it's "operating under reduced capability today, 25 April 2019 due to a Fort Bragg wide power outage...The Emergency Department is open, however, the Urgent Care Clinic is closed until power is restored. Inpatient services are operational."

And then, by the afternoon, the fort's Facebook page published a meme that says "Don't Worry It's Just A.."MILITARY EXERCISE.""

"Good afternoon all! We understand the exercise conducted caused concern for many within our community and surrounding areas...for that, we apologize. However...we had to identify ways to keep #FortBragg mission capable. Department of Defense requires military installations to conduct readiness exercises on an annual basis. The intent is to determine the readiness and resiliency of the installation in a real-world scenario. With that said, our objectives have been met and as many of you know, everything is back to normal. We appreciate your patience and cooperation. Continue to be#vigilant and stay #safe."

Designed to run concurrently with an emergency deployment drill, base officials simulated an environment where special forces were preparing for war, and at the same time, the base was assaulted by enemy cyber attacks. Officials had intentions on bring the base to its knees during the exercise.

"This exercise was not announced in order to replicate likely real-world reactions by everyone directly associated with the installation. In today’s world, cyber-attacks are very likely. This exercise is exactly what we needed to do to identify our vulnerabilities and work to improve our security and deployment posture."

The first rolling blackout struck the base around 10 PM Wednesday. Base officials began turning power to some parts around 11 AM Thursday. It wasn't until 4 PM that base-operations were completely restored.

For base officials to conduct such an extreme, unannounced military exercise that paralyzed the fort's power supply, well, there must be a credible threat lurking around the corner.