South Sudan, the country that fell apart in a month
A man carries an AK-47 as he gets off a boat on the White Nile, in Minkamen, Awerial county, South Sudan, on January 10, 2014
"When it is over we will all be losers in this war," said Mabior Garang, son of South Sudan's late founding president, and now a member of the rebel delegation at peace talks in Addis Ababa.
Even for the most careful watchers of the complex power struggles of South Sudan, the conflict -- and its shockingly brutal nature with neighbour turning on neighbour -- spread very fast.
Jok Madut Jok, a former senior government official and academic now running the Sudd Institute think tank, speaks of a "near total unravelling" that has left South Sudanese in deep shock.
War-ravaged South Sudan is oil-rich, but for once, such resources played little direct role.
Instead, the violence appears rooted in decades-old grievances between former rebels turned political leaders, combined with unhealed wounds left over from the two-decades long civil war that preceded South Sudan's independence from Khartoum.
"This conflict escalated so fast partly due to the history of the liberation wars, in which South Sudanese committed atrocities against one another," wrote Jok in a recent report.
"No accountability for these atrocities was established when those wars ended, leaving gaping wounds in the hearts and minds of so many citizens."
Political opposition to President Salva Kiir had been brewing openly, with his recently sacked deputy and long-time arch-rival Riek Machar accusing him of "dictatorial" behaviour in early December.
Machar infamously fought on both sides during the civil war, a conflict that paved the way for South Sudan to choose independence less than three years ago, in July 2011.
Billions of dollars worth of international aid, advice and development help were poured into the fledgling nation -- often having to build government institutions from scratch -- alongside enormous and often more effective private investment.
But many had still feared that a conflict on this scale was all too possible, amid repeated warnings of rampant corruption -- including the brazen theft of billions of petro-dollars -- and security forces accused of gross abuses of power.
Rapid but poorly done integration of varied rival ex-rebels forces into the army simply papered over deep-rooted divisions.
The army wrested back the town of Bentiu on Friday -- capital of the key oil producing state of Unity -- but it is not yet clear who controls the oil fields upon which over 95 percent of South Sudan's economy depends.
Regional powers -- including even old enemies Sudan as well as Uganda -- are being dragged in too.
"We are facing an unfolding human catastrophe," UN aid chief in South Sudan Toby Lanzer told AFP, after visiting the foul-smelling camp of civilians crowded into a former football pitch at the back of the UN base, too terrified to return to their homes for fear killings might begin again.
Lanzer notes with gloom how he found a newspaper printed the day before the violence erupted on December 15, where the front page carried two key stories.
One noted how President Salva Kiir was to follow the example of the late South African President Nelson Mandela to reconcile political rivals, the other praised the success of an investment conference.
"This is certainly the biggest test this young nation has had," Lanzer added.
"What we have is a huge political struggle, people who have taken positions which are entrenched and civilians that are caught in a situation that is unbearable."
Political conflicts have triggered battles now apparently out of the hands of the leaders who lit the match, reawakening bitter wounds from 1991 battles when Nuer and Dinka peoples fought.
"These are political manipulations, but now the fight has set fire to the grassroots, the problem is tribal," said Paul Manyok, a shopkeeper who fled the fighting in Bor, the largest town now in rebel hands.
Kiir comes from the Dinka people, the largest single group in South Sudan, while Machar comes from the Nuer, the second largest.
The situation is far more complex than an ethnic battle alone: Kiir's army commander is Nuer for example, while Machar's peace talks team includes senior Dinka leaders.
While the stories of horrific ethnic killings grab the headlines, reports are common of people from apparently "rival" communities helping or sheltering each other as well.
Yet many appear deeply pessimistic that when -- or if -- a political deal is struck by leaders at slow-moving talks in Ethiopia, whether the crisis has gone too far to be reined in on the ground.
"I didn't think of my friends before as 'this one is Dinka, this one is Nuer,'" said William Gatwech, 22, a student sheltering in a cardboard shelter in the UN camp Juba.
"But I fear going out the camp because I will be targeted because I am Nuer... that is what they were doing when the fighting started, killing the Nuer."
To the north, another student, Peter Mabior, recounted how Nuer fighters had called out in the Dinka language to people, shooting to kill those who replied.
"What happened cannot be forgotten or undone," Mabior said, after fleeing attacks to join some 85,000 displaced people from the Bor region. "You think we can trust them now?"