JUBA, Sudan » After five decades of guerrilla struggle and 2 million lives lost, the flags are flapping proudly here in this capital. The new national anthem is blasting all over town. People are toasting oversize bottles of White Bull beer (the local brew), and children are boogieing in the streets.

"Free at Last" reads a countdown clock.

But from the moment it declares independence Saturday, the Republic of South Sudan, the world’s newest country and Africa’s 54th state, will take its place at the bottom of the developing world. A majority of its people live on less than a dollar a day. A 15-year-old girl has a higher chance of dying in childbirth than she does of finishing primary school. More than 10 percent of children do not make it to their fifth birthday. About three-quarters of adults cannot read. Only 1 percent of households have a bank account.

Beyond that, the nation faces several serious insurrections within its own sprawling territory and hostilities with northern Sudan, its former nemesis.

It is clearly an underdog story.

So many people here embody the distance traveled and the hopes to come. James Aguto, a former child soldier and longtime guerrilla fighter, now delivers babies. Aguto is a newly minted clinical officer, working in a government hospital, and his journey from taking life to sustaining it makes him an apt symbol for the transition this country is trying to make.

"There was one night I delivered six babies, six babies in one night!" he said. "I was so happy. I was making development here. I was showing that I had skills."

Aguto now wants to be a doctor. "I have that spirit," he explained.

The nation will certainly need it. More than 2,300 people have been killed in ethnic and rebel violence this year, with at least a half-dozen rebel groups, some with thousands of fighters, prowling the bush, attacking government soldiers, terrorizing civilians, and stealing cattle and even children.

The hospital where Aguto works is a case in point. In one bed lies a thin young man with a huge cast on his leg.

"Abyei," the man grunted, referring to the disputed area on the border of northern and southern Sudan that is claimed by both sides. It is considered one of the many potential trouble spots that could plunge this region back into war. He was shot there in May, when the northern Sudanese army invaded.

Nearby is another young man, hobbling around with a walker. "Unity State," he said. "A militia."

He was shot as well, in another tense border area.

Ethnicity is a consistent fault line here. The government is dominated by the Dinka, the biggest group in southern Sudan, and some of the toughest rebel armies are commanded by members of the Nuer, a historic rival.

"This is just tribal fighting," Mustafa Biong Majak, a South Sudan government spokesman, said with a dismissive wave of his hand, arguing that the clashes posed no threat to stability. "Let them die."

But many people here fear that after the glow of independence wears off, the Nuer and the Dinka, who fought viciously during the north-south civil war, will become locked in conflict again. And even within the Dinka-dominated government forces, there are deep problems.

Government troops routinely take sides in local land disputes and battles over cattle, and recently soldiers have been hijacking U.N. trucks hauling food. Hunger is yet another challenge, with more than 3 million people in South Sudan, nearly 40 percent of the population, needing food aid to survive.

Less than 10 miles outside the capital, in the village of Rajaf, people are fleeing the countryside because bandits are killing farmers and kidnapping children. The rule for visitors is to leave by sunset.

"There is no security here," said Rose Bojo, a tea seller.

Insecurity is such a drain on resources that under the current budget, the government of South Sudan spends about $700 million on security-related matters — more than the budget for education, health care, electricity, roads and industry combined.

But this is also a country of obvious possibilities. South Sudan produces about 375,000 barrels of oil per day, and though negotiators are still working on the specific formula of how the two Sudans — north and south — will share the oil, the south stands to make billions from its reserves.

It has land, miles and miles of thick forests and fertile jungles, where the trees drip with vines and branches bend earthward, heavy with fruit. Still, in most villages, there is no electricity, no running water, no metal even. Barefoot boys dusted with the red dirt stirred up by passing trucks sell bottles of honey along the road. The South Sudan government says 83 percent of its people live in thatched-roof huts, a legacy of decades of marginalization.

Even before Sudan declared independence from Britain and Egypt in 1956, southerners were clamoring for more rights and complaining about being treated as second-class citizens.

South Sudan is mostly animist and Christian, culturally more akin to sub-Saharan Africa than northern Sudan, which is predominantly Muslim and dominated by Arabs. Southern rebels fought for years against the central government, and in 2005 the Bush administration helped broker a treaty between the sides that granted the south wide autonomy and the right to secede.

In January, southerners voted by nearly 99 percent to form their own country, which is what will officially happen Saturday in festivities to be attended by high-ranking Western officials and more than a dozen African leaders.

Some of the expected guests, like President Robert Mugabe of Zimbabwe and President Isaias Afewerki of Eritrea, are cautionary tales of what can happen when guerrilla leaders finally take power. Zimbabwe and Eritrea are considered among the most repressive countries in the world. But South Sudanese officials say that they are aware of the pitfalls, and that their government will be different.

"If we had wanted to, we could have declared a five-year transition period from the beginning," said Majak, the government spokesman. "But no, we didn’t do that. We held elections."

For the past six years, the southern Sudanese have essentially been running their own affairs, policing themselves, patrolling their borders, and wooing investment and development aid. International aid organizations are still going to play a crucial role here, especially in health and education. For example, Aguto, the bush fighter turned clinical officer, was trained by AMREF, an aid group. He is now looking for sponsors to pay for medical school so he can become a pediatrician.

"South Sudan started from zero," he said. "Why shouldn’t we be able to transform?"

© 2011 The New York Times Company