The crackle of machine gun fire and the dull thuds of distant explosions reminded 3rd Cavalry Regiment troopers at Firebase Saham that the battle against ISIS was not far away.

Troopers assigned to the Field Artillery Squadron, "Steel," and 3rd Squadron, "Thunder," helped establish the temporary firebase Nov. 8, near Iraq's border with Syria, incorporating Iraqi M109 Paladin and French Caesar 155mm self-propelled howitzer units.

Their mission: to prevent ISIS fighters from crossing the Syrian border into Iraq to escape the offensive in the Middle Euphrates River Valley by providing coordinated and lethal artillery fires against the fleeing ISIS members.

"Not today ISIS!" said Sgt. Doug Moran, 3rd Cav. Regt., Steel Squadron, gun crew chief, after his crew unleashed a volley of 155mm high explosive shells from their M777A2 Howitzer.

The sound of their rounds impacting hadn't faded before the crew was already prepared for the next volley. Fire missions came with little to no notice, and gun crews scrambled to provide immediate fire support.

The Steel troopers brought their M777s to the fight, while the Thunder troopers established the layout of the base and provided security and logistics for the Iraqi, French and U.S. troops.

"The first couple days were pretty austere," said 1st Lt. Michael Roberto, Thunder Squadron troop executive officer. "Guys were sleeping in their kit, sleeping in their trucks."

Roberto's troops were responsible for developing the base plan that decided where everything on the firebase would go. They also coordinated with the Iraqi and French units to incorporate everyone into the base plan.

The Iraqi and French firing units were an integral part of the firebase, providing three distinct artillery units to support cross border strikes against ISIS.

"I don't think there's a single artillery battery in the Army doing what we're doing right now," said Capt. Frank Thompson, 3rd Cav. Regt., Steel Squadron, field artillery battery commander.

"We've jumped to four totally unique locations in the last few months, establishing new firing points from scratch in some very austere locations," Thompson said.

Thompson's battery also coordinated with the French Caesars and Iraqi Paladins to synchronize their fires, delivering fire support across the border into Syria in support of the fighting against ISIS and bolstering the Iraqi border security posts.

"No one else is doing all that," added Thompson.

The Iraqi troops named their firebase "Saham" for the Arabic word "arrow." It was established miles away from civilian populations and postured to provide effective fires against ISIS fighters attempting to cross the border into Iraq.

Logistics are delivered by air and ground, providing the Iraqi, French and U.S. troops with much needed water, food and ammunition.

"The coolest part of establishing this location was the logistical demand and how we sourced the needs of our troopers on the ground," said Roberto. "We did whatever we had to in order to enable our sister units to provide effective fires into the MERV."

The priority on their deployed mission was to secure the perimeter of the firebase and ensure the Iraqi, French and U.S. guns were ready to support fire orders that came their way.

"Because of our proximity to the border with Syria, we're very cognizant of the risk," said Capt. Jordan Marks, a troop commanding officer with Task Force Thunder. "This is what the U.S. soldiers signed up for - to operate in austere locations like this and support the multinational coalition fighting ISIS."

The French Caesars and U.S. howitzers sat side-by-side at one end of the firebase, barrels pointed across the Syrian border into ISIS territory, the Iraqi Paladins nearby with their barrels arrayed to protect Iraqi Security Forces border positions.

The U.S. Army gun crews of "Bull Head" and "Big Rich" lived with their guns. During the day they did their laundry by hand, conducted physical training, maintenance, crew drills and ate their meals on the gun line.

At night, they awoke to the firing of the French Caesars and watched tracer fire along the border where Iraqi Security Forces prevented ISIS fighters from fleeing into Iraq.

The sounds of strikes against ISIS positions in Syria echoed across the border 24 hours a day.

"I think about it every day, every night, when I hear the explosions right across the border," said Staff Sgt. Brandon Cass, Big Rich, Steel Sqdn. "The anxiety is definitely there."

"I've been in combat situations before, been in much more dangerous situations than this. But most of these guys have never deployed. This is their first time," said Cass.

After the first jump to establish Firebase Saham, the gun crews went to work immediately with multiple fire missions to stop ISIS militants on the move toward the border.

"Five days straight we shot," said Cass. "It was non-stop."

Calls for fire came around the clock, and the gun crews executed fire missions night and day, with little to no sleep and the occasional Meals Ready to Eat to sustain them.

"That's all these guys wanna do is shoot," said Cass.

In between fire missions, troopers took advantage of the relative calm to improve their living areas, setting up expeditionary gym equipment, improving dining areas and stringing out hand-cleaned laundry on makeshift clotheslines.

The initial air drops brought supplies that were needed, but not always the supplies the troopers wanted.

"Early on, we got dropped a bunch of "Case A" MREs, which we didn't think was possible," said Roberto.

There are a total of 24 different styles of MREs, divided into Case A and Case B. Each type of case holds a specified menu of 12 MREs.

"When we looked into our MRE holding area there was only Case A," said Roberto. "Even if you had one different MRE for each meal, that still only gets you through 4 days before you start to repeat."

"You know how you try to get creative with how you prepare and mix and match MRE contents? Well, we had to get even more creative," said Roberto.

With no cell phone signal reception and limited internet connectivity, troopers turned to one another during their downtime and formed stronger bonds without the distractions of social media and the internet.

"They have each other," said Roberto. "They play cards, they work out together, spend all day together. And when they get back from the firebase and have better internet, they have more to talk about with their families."

They also reminisced about their experiences from the deployment and their time at Firebase Um Jorais, the first temporary firebase established by Iraqi and U.S. troops in June to support clearance operations in Dashisha, Syria.

"I don't think I've ever been in a more austere place," said Cass. "The heat, there were sand storms, it rained and our only protection from the elements was our camo net."

"We slept, ate, shaved and did everything outside. We put up a shower - just a pallet with two pieces of plywood against a connex box and water bottles," said Cass.

Firebase Saham had some luxuries, like showers and tents, but it was still a firebase and the artillerymen were anxious to get to work.

"If you forget why you're out here, the guns firing at two in the morning will remind you," said Roberto.

During lulls between missions, troopers expressed their frustration of not firing against the enemy and couldn't wait to contribute to the fight which was raging miles away.

"I think it's going to pick up soon," said 1st Lt. Brendan Moreira, the artillery battery fire direction officer.

Moreira led the fire direction center, responsible for coordinating all fires between the three different artillery units and ensuring airspace was cleared before fire missions and commands were passed to the gun crews.

He also coordinated training with the Iraqi Paladin crews, many of whom were familiar faces to the Big Rich gun crew from their time at Firebase Um Jorais.

When the Iraqi and U.S. artillery units met at Firebase Saham, the gun crews immediately recognized each other, waving and shouting out names of their fellow artillerymen. They broke out their cell phones to share pictures with each other, asking about different Soldiers and Marines that they hadn't seen in months.

The Iraqi battery fire direction officer, Maj. Hassan, also served alongside the U.S. troops at Firebase Um Jorais. Once he arrived at Saham, he began inviting the U.S. leaders to eat breakfast with their Iraqi counterparts. They met almost daily and discussed training opportunities, local intelligence reporting and each other.

In the Iraqi tent, everyone sat huddled around a steaming tray of chai tea, boiled eggs and fresh naan bread, baked on site by one of their partner Iraqi soldiers.

Hassan talked about his life as an Iraqi army officer before 2003, then looking for work and finding it in the laundry facility of a contractor supporting coalition forces in Iraq in 2004. He later joined the Iraqi Security Forces as an artillery officer.

At Firebase Saham, he stood shoulder-to-shoulder with U.S. and French artillery units defending his country's border against ISIS.

Intelligence reports on ISIS activities were shared by Iraqi, French and U.S. leaders.

During one breakfast meeting, Hassan said that one of the nearby border security positions saw ISIS movement during the previous night.

"We conducted strikes and small arms fire, and kept them from getting close to the border," said Hassan.

The border positions were often probed by ISIS elements seeking to flee the fighting in the Middle Euphrates River Valley by escaping into Iraq, but the Iraqi Security Forces sent several thousand troops to the border in October and routinely conducted strikes and direct fire from established border positions.

When the firebase was initially occupied, everyone could see tracer fire from interlocking security positions all along the border, said Thompson.

That was in early November, during intense fighting that forced large numbers of ISIS fighters fleeing toward the Iraqi border where they were met by a line of defensive positions and Coalition-led fires.

Hassan worried that ISIS fighters would throw down their arms, change clothes and try to infiltrate groups of refugees fleeing across border checkpoints.

"[ISIS] have nowhere to go; if they stay, they will die," Hassan said.

The Iraqi artillery officers were anxious to get their soldiers into the fight and asked to train with the U.S. troopers as often as possible. Their M109 Paladin self-propelled howitzers were very familiar to many of the U.S. artillerymen.

"The fundamentals are the same, and we use a lot of the same equipment and ammunition," said Moreira.

The Iraqi and U.S. artillery troops trained together on fundamental tasks, sharing best practices on crew drills, equipment calibration and fires coordination.

Their training paid off as the Iraqi, French and U.S. guns conducted coordinated fire missions, delivering their firepower across the border as weather limited the number of air strikes against ISIS targets.

"If weather is poor and air forces cannot fly some of their missions, we are prepared to support the fighting across the border with our own fires," said French army Capt. Clem, the Caesar battery commander.

"We are here together to face the same enemy with U.S., French and Iraqi units on the same firebase," said Clem.

Across the border, in the MERV, loomed the last significant number of ISIS fighters looking for an escape route from the Coalition-led offensive. At Firebase Saham, the gun crews of Big Rich and Bull Head, along with batteries of Iraqi and French artillery, patiently wait, standing ready, to deliver lethal fires at a moment's notice.

"I would never have wanted to go home without coming here, to this firebase," said Moreira.

"This is what we trained for."