One doctor's refusal to abandon thousands of refugees in the border area between Sudan and the new nation of South Sudan has left him in great danger as conflict rages in the area.

This is the story of one man's attempts to bring medical aid to his people, caught up in one of Africa's least reported wars.

I first saw him sitting under a tree, patiently discussing how best to improve the services for refugees with a group of aid workers.

We had been told to look out for Dr Atar.

"You have to meet this guy, he's amazing," one of our contacts said to us.

When the meeting finally broke up and the aid workers wandered back to staring at their computers, he wandered over to us.

At first he did not make much of an impression on me, but I soon realised how wrong I had been.

Dr Atar Adaha Evans used to work in the hospital at Kurmuk - a town just over the border.

A tall man with an open face, easy smile and soft voice, he did everything from surgery to maternity care. But when the fighting broke out he decided to stay, despite the risks.

For months he remained behind, helping where he could, but last December the situation became unbearable.

Loading the equipment he had into the hospital's only ambulance, he followed the path trodden by some 80,000 refugees, and sought sanctuary in the South.

In stages, over 18 days, he managed to get through. He went back to work, still serving his people in a local hospital.

Many medical staff would have thought they had done their bit, but not Dr Atar.

'No protection'

He knew no medical services remained in the war zone - there was nothing for the civilians left behind, or the rebels fighting the government in Khartoum.

My wife asks me if I'm mad. 'What's your problem', she asks? 'Why did you marry me if you wanted to die?' Dr Atar Adaha Evans

So now, when his network of contacts tells him of casualties on the other side, he loads up his ambulance and sets off back into Sudan.

It must be an extraordinary journey, through sorghum fields, and past the giant baobab trees that dot the landscape, picking up the injured along the way.

"Who do you treat?" I asked him.

"Anyone who is desperate," he says. "Civilians, rebel troops, prisoners of war. During Sudan's last war I even treated government army officers. They continue to write to me," he says.

Until two weeks ago his ambulance carried the logo of the Red Crescent Society, but then they objected. So Dr Atar removed it.

"It was no protection anyway," he says calmly.

"They bombed the UN compound in Kurmuk. They bombed Save the Children."

So what does he do when the bombers come overhead?

"Well, I put the ambulance somewhere and lie flat."

But it has sometimes been a close run thing. Once they bombed his tent, just after he had left. He just laughs about it.

And what does his family think about his trips?

"Well", says Dr Atar, "my wife asks me if I'm mad. What's your problem, she asks? Why did you marry me if you wanted to die?"

His eldest son is just as sceptical.

"Why can't you just come home and forget all about it," he says.

Image caption Jammam camp in South Sudan is currently home to over 30,000 refugees

But the doctor is firm.

"I have to remind them it's sometimes necessary to help people who are helpless."

Underneath this quiet exterior there is something truly steely about Dr Atar.

It is the sort of determination that I have met time and again across South Sudan.

This is a land that has known little peace since the end of the colonial era in 1956. Decades of war saw two million people killed.

Some former soldiers I have talked to, walked across the entire width of this vast land to sign up to fight.

The peace agreement between Khartoum and the southern rebels back in 2005 was meant to put an end to all this.

But the peace left many former rebels and their people north of the new frontier. It was perhaps inevitable that war would revisit this part of the world.

There is no sign that talks to break the deadlock are making any progress.

Relations between Sudan and South Sudan are about as bad as they can be, with oil no longer flowing northwards and troops all along the border.

There is not an all-out war at present, rather a rash of smaller, smouldering conflicts on both sides of the border.

As long as this continues, there is every chance that today's strange mixture of rebels, aid agencies and refugees will continue to inhabit this regions, and Dr Atar and his ambulance, making the dangerous journey between them.

As he put it with a shrug:

"My life is in God's hands."

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