When a group of Marines providing security for the United States’ naval blockade of the Strait of Hormuz boarded ships transiting through, the American commanding officer said there was no question how the search-and-seizure missions would go.

“At 2 a.m., when 30 Force Recon Marines step on your vessel, you’re compliant with a capital C,” Col. Chris Niedziocha said recently during a Pentagon briefing following the 31st Marine Expeditionary Unit‘s 10-month deployment.

Once Marines were aboard the “target vessels,” the MEU’s drones and manned aircraft supported them from above, Niedziocha said. “You create this bubble around the vessel. So yeah, they complied.”

He credited his troops, including more than 1,100 Marines and sailors from Camp Pendleton, for their perseverance in adapting quickly from what was supposed to be a routine — and shorter — training deployment to supporting the war against Iran as part of Operation Epic Fury.

“The team never lost sight of the mission and performed flawlessly under the most dynamic circumstances,” Niedziocha said.

While the MEU began the year training in the China Sea with Japanese forces, with a stop in the Philippines, the tempo and mission quickly changed in March when troops were ordered to pivot to the North Arabian Sea to enforce the naval maritime blockade ordered by the Trump Administration.

The Strait of Hormuz, between Iran to the north and Oman and the United Arab Emirates to the south, is a vibrant, critical shipping waterway through which, according to reports from the Energy Information Administration, about 20% of the world’s oil flows.

The ground combat element from Camp Pendleton’s 3rd Battalion, 1st Marines only returned in recent weeks after the lengthy and headline-grabbing deployment.

Niedziocha said the 2,500-strong MEU steamed to the Northern Arabian Sea aboard the amphibious assault ship USS Tripoli, along with its amphibious ready group that included the transport dock ship USS New Orleans and the dock landing ship USS Rushmore.

Marines and sailors on MEUs are trained and ready to respond to worldwide crises, whether they’re called for combat or humanitarian aid. Aboard the MEU are any command, ground, aviation and logistics units that might be needed. Still, the pivot to the Northern Arabian Sea meant a long ocean journey with an unknown end date, managing fear, uncertainty and boredom while trying to stay in touch with family and loved ones back home.

“There were some periods where it was open-ended,” Niedziocha said. “I think that as long as you tell somebody when something’s gonna end, that’s it’s OK, you can survive. But if you don’t know when it’s gonna end, it’s just a lot harder.”

Getting to the Northern Arabian Sea was a 17-day trip.

“You recognize that the ocean is big. I mean, it really is,” Niedziocha said. “And then you realize that you can’t go in a straight line; it’s got to go around the land.”

Once in place, and after the ceasefire was declared, he said the Marines and sailors of the MEU began patrolling with ships and aircraft to help with the blockade.

“We conducted four maritime interdiction operations, three of which culminated in boarding the vessel,” he said. “Two, we searched the vessels and then let them go. One, we actually seized and retained custody of the vessel for about two weeks and repatriated the crew.”

The vessels were mostly oil tankers and cargo ships, each presenting its own challenges, he said, adding that the key was to balance the threat level.  If the Marines expected resistance, they’d board at night, he said. If not, they’d board during the day.

The goal was ultimately to clear the strait, so ship traffic could get through.

At one point in June, President Donald Trump posted on social media that the U.S. would assume full control of Kharg Island and over Iran’s oil and gas market.

Niedziocha said that although the Marines didn’t ultimately move in to take the island, they were the ground troops that were prepared for the mission.

During the mission to stabilize the strait, Niedziocha said tactics included using smaller, faster Marine and Navy units working together.

“We actually, for the first time, demonstrated what we thought we were able to do, which I think is pretty exciting,” he said, referring to a strategy put in place by former Commandant Gen. David Berger’s Force Design 2030, a modernization of the relationship in which Marine and sailor units operate more closely together while also using remote locations for refueling and rearming.

During the four months under U.S. Central Command, the MEU and amphibious ready group logged 1,600 flight hours that included precision strikes and moving 800,000 pounds of cargo. The units also refueled 300 aircraft ashore and underway, he said.

Among those involved from Camp Pendleton’s 3rd Battalion, 1st Marines was 1st Lt. Jacob Meyer, executive officer of a mechanized company of Marines aboard the USS Rushmore.

Now, happy to be home, Meyer said he feels tremendous pride in what he and those aboard the MEU accomplished.

“It was an honor for us to be able to go out there just to see that all the training we’ve done for all the years finally come to the point where we were ready to use it,” he said. “I think we all learned a lot about ourselves and our own capabilities.”

“It was cool to see so much teamwork across the entire MEU and see such an inspiring amount of people come forward, rank-agnostic, with new ideas,” he added.  “It was awe-inspiring to see how clearly capable we are. That was really, really special.”

As part of the headquarters element, Meyer, 26, arrived a month ahead of his unit in Okinawa to work on planning the deployment.

“We knew something was going on over there,” Meyer said of rising tensions in the Middle East, adding that those on board kept up with headlines when they could.

“The general consensus was that we were ready,” he said, once the Marines and sailors were given word that they were heading out to support Epic Fury. “There was a fair amount of uncertainty; we didn’t know what to expect once we got out there. There was a good amount of excitement and apprehension, but the understanding that we knew we’d be ready.”

During the trip to the Middle East, Meyer said the Marines and sailors kept busy training and maintaining the vehicles and equipment. They also made sure to get at least six to seven hours of sleep.

“We trained day and night to make sure we were ready for whatever was asked of us,” Meyer said. “We did gun shoots on the flight deck, numerous classes each day, piled on top of meetings to go over all the contingencies.”

Standout moments were the incredible sunrises and sunsets, he said, and unbelievably dark night skies filled with stars.

“You get very close with everyone on the boat,” Meyer said. “I will have lifelong friends coming out of that. Literally, everything you need to know about a person and don’t want to know. You’re eating every meal, watching movies when you can in your spare time, having in-depth talks about your families and who’s waiting for you back home.”

After some time, though, Meyer said, the monotony of being out to sea sets in, even with regimented daily schedules.

“The days blend together,” he said, adding that most of the time the seas were calm and the weather was sunny. “There were a couple of days of choppy seas.”

Once in the strait, Meyer said the unit’s main focus was defending the ship and preparing for potential conflicts. To do that, he said, Marines and sailors rehearsed drills multiple times a week, simulating an attack.

“It’s a pretty high-traffic area of the world,” Meyer said, describing the large body of blue water where he saw everything from small fishing boats to large commercial oil tankers.

In the four months Meyer was in the straits, he said he never felt apprehensive that something would go badly.

“It just goes back to us relying and trusting the training we had done,” he said. “We were ready for whatever came our way.”

During their pre-deployment training, Meyer said the Marines and sailors had trained on several new types of technology and drones, but new tech still was making its way to the group.

“I was able to dig into that quite a bit,” he said of getting the new technology and testing it. “It was cool to see it work for us.”

Technology has definitely been a defining characteristic of this war, Niedziocha said.

“The Iranians were very creative and innovative, and they embraced unmanned systems,” he said. “Every part of the force was watched by Iranian UAS and intelligence, surveillance, and reconnaissance assets.”

“One of the challenging things is the rate of absorption and the pace at which these service investments are being fielded to the fleet; it’s almost a full-time job keeping up with the new gear,” he added. “You always want more. Nobody’s ever said I’m good, but in terms of what we had to do, I never felt like I had a real capability gap there.”

“You figure out how to use it, integrate it, do it safely, do it intelligently; that’s really important,” he said.

Beyond the security and technology challenges, though, Niedziocha said, the most challenging job was probably managing the “human landscape.”

“You’re managing this sociotechnical organization; it’s its people, it’s things, it’s rules,” he said. “But the human factors, the fear, the uncertainty, managing boredom. These are such good people; they’ll work themselves close to the limits of human endurance. If you let them.”

While Meyer had to make sure his teams were trained and ready for anything that came their way, he agreed that among his greatest challenges was the human side of the deployment, too.

Since the war began, there have been reports of supply chain issues among MEUs and aboard Navy ships.

For a while there, Meyer said meals got to be a bit monotonous with the supplies available, “but we never went to bed starving.”

More challenging was being away from friends and loved ones for 10 months, he said.

“Life still goes on back in California, especially for our Marines with families back home,” he said. “Negative life events happen. People pass away, and people get sick, relationship statuses change. Normal pieces of life that don’t go away just because we’re gone.”

“I think managing that is the most difficult thing,” he added, “while still providing the best opportunities for our Marines; that’s the most crucial thing.”