In a dark room two nights before going to war a boy from Lower Saxony talks about the day of his death. Adnan is small person, 24 years old, Yazidi, German; he has a big nose and nice brown eyes. He comes from Bad Oeynhausen. He drank beer in the spa Gardens there and played football on the lawn, and he stood in the assembly hall wearing a black jacket and received a certificate. Now he is lying on a bed in Dahuk in a town in northern Iraq in the Kurdish area which has become the front in the war against the “Islamic State” (IS). He is hoping to meet his father, the Lion of Sinjar. He hopes the Yazidis are going to win. In Dahuk there is no electricity. Adnan would like to sleep but he can’t. He is wondering whether he will survive this trip. He’s only been in an aeroplane twice in his life. He has only ever been to Iraq once and that was to visit relatives. He has never been in a war. It is supposed to start the day after tomorrow when the wind is not too strong and the fog is not too thick for the helicopters. Adnan waits anxiously.

When the electricity comes back on and the lights flicker he downloads his messages and e-mails. One of them that he has been waiting for is from the CDU. It says: “Please excuse to delay which has been caused by the high volume of enquiries”. It says that his dismay about the situation in Iraq is very understandable. It also says that the conflict can only be resolved on the political level and long term. Yours faithfully. Adnan puts the mobile phone down. “If people respond so slowly we will soon be wiped out,” he says. It is because people respond so slowly that he made the decision to go to the mountain himself. He bought German painkillers and Russian night-vision glasses, cigarettes for the troops and warm trousers for his father. Everything is lying in a big heap next to his bed and Adnan hopes that he will be able to get it all in the helicopter, including his trolley bag which makes him look a bit like someone on vacation who has become lost on the way to a holiday club. It is early December and an offensive against the Islamic State is going to begin in two weeks. It will create a corridor through the area under siege. But for the moment there is, as has been the case for months, only one way to this mountain in Sinjar, i.e. by air. The IS fighters surrounded the mountain and also the 10,000 Yazidis who had escaped in August when IS took the south side of the mountain and Sinjar.

Tens of thousands of Yazidis escaped at that time; 80,000 went over the mountains in a northerly direction whilst 10,000 remained because they could not go on or because they believed they were safe on the mountain. The Iraqi army has an air passage to help people in the most urgent need. But there is a lack of food, clothing and medicines. There are not enough helicopters. One of them crashes and two were shot down by IS militias.

Adnan says that what will happen on the day of his death is already written on his forehead in invisible letters. This is what he believes. It is the belief of the Yazidis, his people. “It is already decided,” says Adnan and he becomes quiet because he does not know the date written on his forehead.

The destination of this journey is the temple at Sherfadeen, the second most important holy place of the Yazidis, the grave of a Yazidi resistance fighter who fought against the Mongols in the 13th century. That is where Adnan’s brother, cousin and his father, Kassim Schesho, are fighting. He had worked in the town council at Sinjar and was one of the last to leave the city when it was taken by the Islamic State. He is now waging a battle in the mountains at Sinjar. Adnan’s dream is that he will be able to liberate the holy pilgrim sites at the end of this trip. It is not a realistic hope.

IS is firing mortar shells and rocket. Suicide bombers use armoured military vehicles and explosives in their attacks. A couple of days ago an IS Humvee vehicle made it as far as the last barrier. In recent weeks before the offensive it looked as though nothing could stop the attacks by IS – not the US air strikes or the PKK guerrilla attacks nor the Kurdish Peshmerga army.

Two days after the sleepless night in Dahuk Adnan is standing on the helicopter landing pad, a dusty field to the north of the Tigris. In a hall they are heaping up sacks of flour whilst helpers are sorting out tents for the mountain. Soldiers are getting ready – men smoking cigarettes are standing around in silence. Adnan is wearing jeans and a green jacket around his shoulders which he bought at home at Intersport. He drags his chequered suitcase behind him. “I think they are coming,” he says.

There is a drone in the distance – three Russian helicopters appear on the horizon, clumsy vehicles built in 1964. They have a heavy landing on the airfield. The wind from the blades causes those standing around to stumble. An Iraqi three-star general in a black flying jacket gets out, takes off his sunglasses and starts shaking hands with people.

Those who are standing around introduce Adnan to him as the son of Kassim Schesho, the “Lion of Sinjar”. “Your father is a hero,” says the General, “I admire him.” “Thank you,” says Adnan. Then he moves back to his suitcase. These days he often hears that his father is a hero, and he always says in response that his father does not want to be a hero. Nevertheless, every Yazidi is aware of the man who was born near Sherfadeen, was a political prisoner in Iraq and Syria, went to Germany and returned to Iraq after the fall of Saddam Hussein. They call him the Man of the Mountain or the Lion of Sinjar. He is the man who sits in the temple at Sherfadeen with a couple of other determined men to defend the place of pilgrimage against the Islamic State. This is the man who, as soon as IS raised its head, called all his friends and said: “Come here and bring weapons. Don’t do it for me, do it for Sherfadeen.” Rappers sing on YouTube about Adnan’s father: “The great rescue – with Kassim Schesho – taking cover.” Adnan is one of ten sons. For him Iraq was only something his father told him about. Whilst his father was fighting on the Yazidi side, he left school and washed up plates and made burgers. He broke off his professional training, did basic military service in Delmenhorst and worked in the German Army Aviation Corps in Bückeburg. He was wrapping up parcels in the army. Then he left. Now he has seven months’ transitional allowance. “Quite honestly, I messed up,” says Adnan. And there is something else that he cannot forget: when he last visited his family in Iraq he left on the day when the fighting started. I was the German and I had booked the return flight a long time beforehand,” he says. Now he is here to make up for that mistake.

Perhaps he will manage to be a good son on an island in the midst of enemy territory. On the helicopter landing pad a dozen Peshmerga soldiers run into the helicopter carrying big cartons and squeeze into the loading bay. There are a couple of aerial gunners at the side doors. The general starts the engine. Adnan sends a text to one of his brothers: “We are taking off now. Don’t forget what I told you.” He reminds him, for example, of the vital necessity to change the electricity provider because of the high tariffs. Adnan sees rough landscape with a few trees sweeping away down below. It is the Al-Jazira plain in Mesopotamia between the Euphrates and the Tigris, an ancient land. According to tradition Abraham passed through this territory. This is where his ancestors built the Tower of Babel. This is where writing, law and agriculture originated. This is where civilisation started. Now the fighters with black flags live down there. The Yazidis say that they are not human. They have proclaimed a caliphate there with laws similar to those seen 1400 years ago. They plunder villages, keep slaves, sell hostages and decapitate people. The aerial gunner is aiming at the ground, he is on the lookout for enemy artillery. Adnan presses his face against the window. The Islamic State regards the Yazidis as heretics and idolaters. God says they must be converted or die. The aim is cultural and religious eradication of the Yazidis’ identity. They have been persecuted for centuries as devil worshippers because they believe in the fallen angel Tawuse Melek who extinguished the fires of hell with his tears and was pardoned by God. The Yazidis have always been persecuted. Muslim Kurds burned their houses down, Ottoman sultans and Iranian shahs filled in their wells and Turkish governors called on people to hunt the Yazidis down. Saddam Hussein had their villages destroyed and mullahs in northern Iraq preach that the Yazidis must never be happy again. According to their own figures there have been 73 attempts in history to wipe out their people. They say that the current one, the 74th, is the most serious. Saddam Hussein, says Adnan, only destroyed their villages. IS takes their women and slaves.

Their mountain at Sinjar has been the ultimate emergency refuge for 700 years. “Without it we wouldn’t still be here,” says Adnan. After flying for half an hour from Dahuk we see the mountains rising almost seamlessly from the plain, a mass of rock, 70 kilometres long and 20 kilometres wide. According to the Yazidis’ belief it was here at the top peak, nearly 1,500 metres high, that Noah’s Ark reached land after the Flood. Now the helicopters land here. From above we can see the encampment and the refugees waving. The landing places are secured by barbed wire and soldiers, partly for protection against their own people. When refugees stream towards the entrance, when they try to reach the rescue helicopters, the aerial gunners kick them in the face with their boots. A few days ago a man clung desperately to the runners as it was taking off before his strength gave way and he fell. Adnan has arrived. He is standing at the top of the mountain with his suitcase. “Let’s find my father,” he says. The refugees have piled stones on top of each other up to knee height and stretched tarpaulins over the top of them to make dwellings. They chop up the last oak trees for firewood. Winter has arrived. In front of the defunct radio masks there is an ambulance with a broken windscreen. The tent has a triangular entrance which is flapping in the wind. Behind it is garbage and upturned cardboard boxes: this is “the hospital”.

There are crashing noises and the sound of explosions coming from the plain. Clouds of smoke are rising. The refugees on the mountain have to watch while the jihadists in the valley are blowing up their houses, street after street, village after village. Once the offensive begins, it means those who return will find their homes in ruins. Adnan finds his father under a tarpaulin stretched out next to a truck in front of the ashes of a fire which has nearly gone out. The Lion of Sinjar is conferring with a Peshmerga general. They are planning the offensive which is imminent, the one which was really supposed to have started last Thursday. He hears them chatting. The general asks Adnan’s father “When are you coming to my place for a visit?”. This is a Kurdish invitation, a visit shows respect. “Bring me 600 men, like you promised, and artillery, then I’ll come and spend 10 days at your place.”

Then the Lion stands up and turns to his guests. Approximately fifty men are standing around the tent: helpers, soldiers, refugees and journalists. Somewhere amongst them is his son. Adnan makes his way forward. His father is waiting but he has to remain in the role of an army leader. “Hello father,” says Adnan. He kisses him three times on the left cheek, then he takes his father’s right-hand, raises it and touches it with his lips to show respect. And his father kisses him on the forehead. This is a blessing. They exchange a few words: “What have you brought?” “Marlboro Gold – what you wanted,” says Adnan. “The real thing?” – “Yes”. “Good.”

It is a brief reunion. Adnan’s father has to fly with the Peshmerga general to Dahuk to do a deal with the Kurdish President Barzani to get more weapons. Adnan is to wait at the bottom of the mountain at the holy site of Sherfadeen until his father returns. The son is to stand in for him as the defender of the holy site.

Adnan says it was the greatest moment in his life when his father stood up to greet him. Four hours later he reached a place without electricity. Sherfadeen. The way here consists of a stony track that runs past burned-out vehicles. Children’s’ shoes lie at the side of the track. Two men with bazookas and a machine gun accompany Adnan to defend him against the “jihadists” if necessary. This is what they call the jihadists – they pronounce it in a drawn-out way and an unpleasant tone: jihaaadist. “Where are they shooting from then?,” Adnan asks. “From Sununi,” says one of the men. “Where is Sununi?,” Adnan asks; he doesn’t yet know the names which used to mean home for the soldiers but which has meant great danger for months now.

Dogs howl at the full red Moon which is shining above Sherfadeen. There are thirty houses here on the mountain slope. The soldiers are entrenched in those that have not been abandoned. There are white gravestones around the entrance to the place. Behind the olive trees there is a large banquet hall where people from the villages used to dance after weddings. Now Adnan’s father keeps ammunition and flour here. On the wall someone has written: “We will fight to the death”. This is Adnan’s new abode. In the hall a woman puts out a blanket on the ground for him. There’s no mobile phone reception. Adnan plays the Super Mario game on his phone. “Turn the light off because of the snipers,” says the woman. There are about twenty men sitting with Adnan in the dark. They talk about weapons, ammunition, the last attack and the next one. “If we get artillery, we can retake our villages,” says one of the men. The heroes here include one man who they call Rambo, a fighter with a dark complexion and a leather jacket who always carries a bazooka over his shoulder. Or the 18-year-old Khalaf Said who used his bare hands to unjam the shell in a mortar tube. Adnan likes listening to Beethoven. His favourite film is “The Big Lebowski” with Jeff Bridges. His only offence so far was riding a bicycle without a light for which he received a fine of 10 euros. Adnan says Bad Oeynhausen is his home. His brothers work at VW and Hettich and study law – a German life. And yet he was always Adnan, the Yazidi. He had to listen to people telling him that his German was quite good for a foreigner. “I have been German for 24 years,” he says, “of course I speak good German.” He says that when he’s with Germans he can see it in their eyes, that he will never really be accepted. In the eighth grade he gave a presentation and everyone stared at him when he said that Yazidis can only marry Yazidis. It is a protective mechanism for a nation that has always been fleeing.

A new day begins. On the side of the mountain at Sherfadeen the men have made words out of stones – the letters are a metre high: “Help us”. A group of fighters approach Adnan. They want more ammunition from him, the son of the Lion. “Give me time to arrive first,” he says. He decides to visit Haydar, his cousin who lives in the last house before the front where the windows are blacked out with cardboard to make sure no rays of light can be seen outside. Haydar is sitting in a garden at the front next to a bed where onions are growing. It’s quiet at the moment – no shooting. The cousin is a friendly man with a moustache, an MP in the Kurdish parliament, formerly the manager of a Burger King outlet in Bad Nenndorf. He studied politics. His daughter is a structural engineer in Germany. Now he is here fighting against the Islamic State. Haydar is tired and you can see the tiredness in his eyes which have seen so much. In a recent battle he had to leave his best friend behind. He called out to him three times but there was no answer. The memory haunts him. “I do feel sorry but otherwise we wouldn’t have got away either.” A shot can be heard in the distance. Haydar’s men are running back and forth excitedly on the roof and speaking into their radios. Haydar carries on talking as though the telephone had just rung. Adnan says the enemy is not just their enemy but the enemy of the whole world. Two cars are approaching. They are going to fire mortar shells. Haydar excuses himself for the interruption. He turns and takes hold of a heavy Browning machine gun mounted on brickwork. Two men pass the magazines to him. Haydar pulls the lever, pulls the trigger and fires a couple of shots at the cars. He raises his hand, says “ok, that was enough!” and turns around again. The cars turn away. “We had al-Qaida,” he says. “That was bad. Now we have the jihadists. They are even worse. I sometimes wonder what might be coming in the future.” The shooting starts in the afternoon. Heavy shells land next to the pilgrim site. The men take cover in the hall. The windows rattle when the shells land close to the building. Later they collect the shrapnel as souvenirs. When the number of shells landing increases in the evening, the electricity comes back on and the men watch the Champions League game FC Basel versus Real Madrid on television. Real is winning which doesn’t interest the men especially – they are all fans of Bayern Munich.

After the attack, in the evening, Adnan stands in the garden and holds up his mobile phone. There is a place by the washing line where the fighters can sometimes get reception if they hold the phone at just the right angle. Adnan manages to contact his family. We hear excited voices, and he says: “Yes, there are more to shells landing around here. But that’s just normal.” But then he wants to write to the German MP for the Minden-Lübbecke constituency, Achim Post. “Hello Mr Post,” he writes, “We need food and water but above all HEAVY WEAPONS. The IS militia fires at us every day with mortars and rockets, and we haven’t got enough ammunition.” He spends ten minutes trying to send the text message to Mr Post and then he gives up. “I can’t get a connection to Germany,” he says. He has stopped shaving; he is gradually growing a full beard. He has swapped his Intersport jacket for a khaki-coloured military jacket. On top of it he wears a waistcoat with magazines. “It has to be like a second skin,” he explains “so that it feels natural when there is a battle.” At night he hears the snatching of cartridge belts and the clicking of safety catches on rifles as well as the other men coughing and eating noisily. At home in Bad Oeynhausen he would hear the frogs croaking, and when he looked out of the window he saw the swing in the neighbours’ garden and the ridge on the Wiehen Hills. The bath was tiled, and he ate what he wanted. Now he sleeps on the floor and eats bulgur and thin slices of bread. Every lemon is a precious delicacy. The toilet is a hole in the ground. The wind blows cold air through the broken windows. Dogs scavenge for food. But Adnan is now where his father was born. He looks content.

In the hall he tells the story of his first day at school when he was six years old. His father walked with him and at some point he asked him why they were not going by car. “I am only coming with you once,” said his father, “from tomorrow you’ll have to go on your own.” Adnan no longer says that home is where you were born. He says it’s where your place to be. Previously Adnan liked to sleep for a long time but now he gets up at four in the morning to check those on guard on the roof. He says things like: “You’ve got to conquer and destroy the enemy. Unfortunately, the enemy is not stupid. The enemy has rear cover.” The war has changed him in just two weeks. He has found a purpose. He has given it a place. He is no longer Adnan, the Yazidi. He is Adnan, the son of Kassim Schesho, the Lion of Sinjar, the Man of the Mountain. He keeps the key to the ammunition room and he resolves disputes. He also looks out for spies.

Adnan, are you afraid?

“Not for myself, if the worst happens it happens. I’m just afraid for my family.”

How long will you stay here?

“Months, perhaps a year”

What are you going to do here?

“Help the family. Defend the temple. I want to live, not just exist.”

He was never a great believer, but now the war has awakened his faith. He needs it because it explains his journey. Only if we defend ourselves will Sherfadeen, the holy site, protect us, he says. In the evening an old friend of his father comes to him. He speaks of the dreams of his childhood, past lives and future lives, soul brothers and the Zamzam Well in the hidden valley of Lalisch. He says that if they lose their faith they lose everything.

Adnan says that people could not always rely on him before but now they can. One might even say that the war has made Adnan into a better person. Young men from Dinslaken and a former rapper from Berlin fight on the IS side. Someone from Lower Saxony who used to sell burgers is fighting on the Yazidi side. It doesn’t all really make sense, but then this is war.

On Tuesday in mid-December, a few days before the start of the offensive which will break open the IS siege, the holy fire is lit in the temple. In the mausoleum at Sherfadeen an elderly man from the village, the sheikh, carries out this rite. He brings a Kalashnikov with him.

The temple is really only a small chamber made of stone, but for the people here it is everything. They no longer know exactly what Sherfadeen was – knowledge has been lost because they have been on the run for centuries. There is no holy scripture; everyone has different accounts and different stories. Only the rituals remain the same – they have always been passed from the fathers to the sons. Adnan goes through the stone door and kisses the entrance. “May your wishes be granted,” says the old man at the entrance. The sheikh calls out the names of those who are present and blesses them. His cousin Haydar can’t come because he is needed at the front. The wind howls around the temple. The fire lights up Adnan’s face. He lays his hands on the stone alter. He says that here you need to make a wish with a pure heart.

In the evening he says he doesn’t know exactly what people here wish for. But Adnan believes they wish for the dead to rest in peace, the women to be free and for the hungry to have food and for those who survive to win the battle. And that his father may return safely.

From outside we can hear the sounds of houses being blown up, and the wind is increasing. The old sheik approaches the temple and points to the holy mulberry tree in front of the entrance. He explains that everyone who comes to the holy place takes a leaf from this tree as a sign of his faith. One of the young fighters next to him opens his wallet which contains a small, crumbling leaf.

Tonight the Islamic State is going to attack again. Up on the mountain at the machine gun post one of the fighters points to the last mortar shell in the ammunition box. The men in the mountains have fixed an extra canister to their rifles. They would prefer to kill themselves rather than fall into the hands of IS.

The end of Sherfadeen would mean the end of all the buildings in the villages that are conquered by IS: broken stones between damaged graves. But that’s not what happens, at least not this time. A few days later Adnan’s father returns, and 500 Kurdish Peshmerga fighters reach Sherfadeen. The temple is free. Trucks packed with grain and blankets reach the mountain. The wishes made under the mulberry tree have been granted.