Syria Democratic Forces (SDF) special forces sit inside a tank near Manbij, in Aleppo Governorate, Syria, on June 25. (Rodi Said/Reuters)

More than a month after it began, the battle for the Syrian city of Manbij drags on.

Now surrounded on all sides by a coalition of Kurds and Arabs, known as the Syrian Democratic Forces, and supported by U.S. Special Operations forces as well as dozens of airstrikes, the motley assortment of troops is slowly rooting out Islamic State fighters one block at a time.

Yet, despite gains around the city, one cluster of buildings at the southern tip of Manbij has turned into a small redoubt and a symbol of the Islamic State’s determination to hold its territory. The structures, a series of grain silos, elevators and administrative buildings, have been hit by numerous airstrikes since 2014. And despite various reports of their seizure by the U.S-backed forces, they still appear either to be partially held by ISIS fighters or so laden with mines and booby traps that advancing troops are unable to enter.

Positioned a little more than a mile from the center of Manbij, the grain silos are a dominating piece of terrain that provides their occupants an unfettered view of the city. For the U.S.-backed Syrian forces, this means that their American advisers would be given an observation tower for calling in airstrikes while their Syrian comrades cleared the rest of the Manbij. The Islamic State knows this and, in turn, has fought doggedly to keep them, littering the buildings with snipers and explosive devices.

Initial reports on social media indicate that Syrian Democratic Forces began fighting around the grain silos in the first five days in June, a little more than a week after the campaign to take Manbij began. As the U.S.-backed forces began to encircle the rest of the city, ISIS refused to budge from the grain towers. It is unclear how many airstrikes have been called in on what appear to be reinforced concrete silos, but pictures and social media reports indicate that they have been continuously hit since the beginning of the month.

Smoke and flame rise after what Syria Democratic Forces fighters said were U.S.-led air strikes on the mills of Manbij where Islamic State militants are positioned, in Aleppo on June 16. (Rodi Said/Reuters)

Footage, which appeared Monday on YouTube, appears to show an airstrike hitting the silos, but it is unclear how recent the video was shot. Syrian Democratic Forces have repeatedly said that the silos are under their control, however social media reports have contradicted those claims or have said that the advancing forces only partially control the compound. This is likely because Islamic State fighters, like they have in other battles in Iraq and Syria, are moving through extensive tunnel networks that allow them to reoccupy previously vacated positions.

“The grain elevators there have been key terrain and offer commanding views of the city and surroundings. It’s definitely a tough fight,” said a senior defense official, who spoke on condition of anonymity to discuss an ongoing operation. “[ISIS] doesn’t want to lose Manbij. The strategic implications are huge for them.”

Modern grain silos are constructed of reinforced concrete as the material is fireproof and is well suited to keep their contents dry. Aside from agricultural use, reinforced concrete has also been the preferred construction material for numerous defensive fortifications, including Hitler’s Atlantic Wall.

The Islamic State’s almost month-long defense is reminiscent of another group of troops that refused to give up a concrete silo at the Battle of Stalingrad.

Besieged by the German Sixth Army, roughly 50 Soviet troops from the 13th Guards held out for five days in September of 1942, forcing the Germans to bypass the silo.

“In the elevator the grain was on fire, and the water in the machine guns evaporated. The wounded kept asking for something to drink, but there was no water nearby. This was how we defended our position, day and night. Heat, thirst, smoke – everybody’s lips were cracked,” recounts Andrei Khozyainov, one of the few soldiers that survived the battle, in the book “Voices from Stalingrad.”

Eventually, the majority of the silo’s defenders were killed, but not before repelling numerous German infantry and tank assaults.

While the fight for Manbij is nothing like the combat seen in one of World War II’s toughest battles, the city is significant for the Islamic State as it has been under its control for more than two years and has served as a key hub for transiting foreign fighters and supplies flowing from the Turkish border.

The Pentagon and White House have championed the Syrian Democratic Forces and their successes around Manbij and in northern Syria as proof that the U.S. strategy to defeat the Islamic State is working.

According to Pentagon Spokesman Navy Capt. Jeff Davis, the force fighting in Manbij is composed primarily of Arab fighters, a demographic that will be key to holding and rebuilding the city.

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