An estimated 2.5 million people live in and around the city of El Fasher, the capital of North Darfur in western Sudan.
But it's now at the centre of a devastating struggle between two warring factions, which has stretched into its second year.
The Rapid Support Forces (RSF), an ethnically-Arab paramilitary group, has been fighting the Sudanese Armed Forces for control of the country.
The civil war – triggered in April 2023 by a dispute between the leaders of these two factions — has reignited old ethnic divisions between Arab and African Sudanese.
It has also led to multiple allegations of war crimes and atrocities and created the "world's largest hunger crisis", according to the World Food Program.
The city of El Fasher lies in the balance and its fall could determine the outcome of the war.
The RSF is currently attacking the city from three directions — north, east and west.
[DATAWRAPPER map of Sudan]Analysts from the Humanitarian Research Lab at Yale University can see "technicals" – utility vehicles, which typically have 50 calibre machine guns mounted on them – from the RSF inside the city on satellite images.
"At this point, the majority of the city has been reduced to rubble by Sudan Armed Forces air strikes and Rapid Support Forces bombardment," said Nathaniel Raymond, the director of the Humanitarian Research Lab.
Satellite images taken between November 3 and 8 show damage from shelling around El Fasher's Grand Souk (market), near where the Sudanese Armed Forces were based.
There are craters and damaged buildings visible in the centre of the second image that were not present earlier.
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Shelling in this area indicates direct attacks on the Sudanese Armed Forces and an ability of the RSF to attack the centre of the city.
The war comes to El Fasher
Analysts from the Humanitarian Research Lab can also see artillery damage to buildings and have been tracking the use of a particular mortar shell used by the RSF.
They can see the RSF is directly attacking the headquarters and air base of the last Sudanese Armed Forces detachment inside El Fasher, the Sixth Infantry Division.
"The 6th Infantry Division headquarters building is near the Grand Souk in the centre of the city. The majority of the remaining Sudan armed forces are at the air base and the air base is taking fire now," Mr Raymond said.
"We can see munition craters. We can see damage to buildings. We can see thermal scarring and that's an extremely troubling development.
"Because we can see that some of those munition craters are small bore mortars, likely consistent with a weapon, like the M224 mortar.
"And why that's bad is that those mortars have a maximum range of 3.5 kilometres, which means now we can say forensically that Rapid Support Forces are under 3.5 kilometres from the last stand location of the 6th Infantry division.
"They are probably closer than that."
What the fall of a city means for Sudan
It's been very difficult for journalists to cover Sudan's horrific civil war, with the government denying visas and armed groups detaining media crews that have made it into Sudan.
Mobile phone towers around much of the country have been destroyed, leaving satellite communications as the only way to get information from inside many parts of Sudan.
Satellite images are one of the few ways to see what is happening.
The scale of death and horror in Sudan – 11 million people displaced, millions starving, myriad atrocities and rampant disease – dwarfs more prominent conflicts in Gaza and Ukraine.
But the war has not attracted the same international attention.
Now, the fall of El Fasher, Mr Raymond said, could be the worst catastrophe in a war that has already been filled with immense suffering.
"This would be the most significant event in the war today," Mr Raymond said.
"The reason why, is that with the fall of El Fasher, the Rapid Support Forces will control Darfur.
"They will be able to complete the Darfur genocide largely without resistance from the international community.
"They can complete the liquidation of the non-Arab tribes of Darfur and they will be able to go and hit all the villages they've missed in the past few weeks."
The RSF has reportedly denied allegations it has been committing genocide in Darfur.
Displaced people forced to live in tents
The greatest fear for aid groups is that once the Rapid Support Forces conquer El Fasher, they will attack an Internally Displaced Persons (IDP) camp called Zamzam, which is 12 kilometres to the south.
Hundreds of thousands of people have fled to the camp, many from El Fasher.
"We don't have our homes anymore, there are no schools and the malaria is spreading everywhere. The famine is hitting too," Aisha Suleiman Bahreddine, a 43-year-old mother of seven, told the ABC using satellite internet from inside Zamzam camp.
"The elderly people cannot move anymore. We lack food, children's food, and for the elderly people.
"Soon it will be monsoon. We have no cover whatsoever. Nothing to protect ourselves from the cold.
"We made a tent with our clothes, Sudanese textiles. Life is very dire, life is so difficult."
She said her family eats one meal a day: the Sudanese traditional dish made of fava beans.
"Only one. We haven't eaten yet, and yesterday we ate one meal," she said.
The people in the camp are relying on traders who bring food sporadically, as most of the major aid groups have evacuated.
"The conditions are terrible, the humanitarian situation has deteriorated even beyond what we imagined," Gaffar Mohammud Saeneen, a political activist who co-chairs the small, independently-funded Team Zamzam aid program in the camp, told the ABC.
"You cannot describe the suffering.
Researchers have been able to track the expansion of Zamzam camp from the air.
As the RSF advanced into El Fasher, civilians began fleeing. Researchers at the HRL detected a large number of new temporary structures (tents, shelters) in previously vacant areas of the Zamzam IDP camp in September and October.
You can see them in the centre-right of the bottom image. Coupled with images showing large numbers of people moving south on the road from El Fasher, they can see that residents of the city have fled to the camp.
Foreign aid workers have evacuated but the camp residents are unable to leave, because the Rapid Support Forces control the area around Zamzam.
The people in the camp have already suffered in the fighting so far.
"We came here because our neighbours got hit and they were killed. There was no one to help them," Samira Mohamad Abdallah, a mother of six from El Fasher, told the ABC.
Carpenter Bilal Ishak Youness came to the camp out of fear for his wife and daughter.
"We fled El Fasher because of the rape fear. There is no safety because of the militia. We are afraid of Rapid Support Forces militia men," he said.
Satellite images analysed by show the camp residents are preparing to be attacked at any moment.
"They're building fortifications at the IDP camp and it is clear that they think they're going to be attacked," Nathaniel Raymond said.
"Zamzam is the largest remaining IDP camp in Darfur of the survivors of the first Darfur genocide in the early 21st century and the people in Zamzam camp are primarily Zaghawa (people)."
"The Rapid Support Forces since March have burned to the ground most of the Zaghawa communities surrounding Al Fasher.
"And when they entered the eastern south-eastern side of El Fasher during the late spring, early summer, the Rapid Support Forces started burning houses individually in the Zaghawa neighbourhoods.
"So it is highly likely that the Rapid Support Forces will attempt to liquidate the Zaghawa en masse."
Hopes rest on a ceasefire
The people in the camp are already close to starving.
The international experts who assess food availability in July classified conditions in Zamzam and around El Fasher as a famine.
Nathaniel Raymond from the Humanitarian Research Lab said the fall of El Fasher would make conditions even worse and lead to mass starvation.
"Sudan's the largest humanitarian crisis in the world, it's the largest displacement crisis in the world, it's the largest food security emergency in the world," he said.
"It is a level of starvation now, that on its current trajectory, will likely exceed in terms of severity and scale the suffering we saw in 1984/85 in the Ethiopian famine.
"We are on a trajectory in terms of potential starvation in Sudan were it may only be rivalled by the Chinese Great Leap Forward famine in the mid 20th century, so this may be the largest starvation event globally since the 1950s."
Aid groups said the only hope for Darfur is an immediate ceasefire and enforcement of an arms embargo on the warring parties in Sudan.
"We've been calling for this conflict to end," Mohammed Abdeladif, Save the Children's interim country director in Sudan, told the ABC.
"We've been calling for a UN resolution for a ceasefire to take place and an immediate and sustained effort to open supply routes and secure ceasefire are critical to prevent the famine crisis from worsening and further atrocities happening.
"That really requires concerted action at the national, regional and international levels.
"Pressure has to really mount on all parties to the conflict, to end the fighting and stop impeding access."
