DUK PADIET, Sudan  The word went out on a Friday. Chibetek was coming, with warriors and a grudge to settle.

The whole village sprang into battle mode. Boys grabbed rusty rifles, women ran to the river to hide in the water, old men stood sentry on the village outskirts, training their yellow, rheumy eyes on the vast savannahs and malarial swamps that have kept this region cut off for decades.

And when the warriors did come, the villagers said, there were hundreds of them, maybe thousands, pouring through the chest-high elephant grass with machine guns and rocket-propelled grenades, dressed in crisp new uniforms that implied a level of military organization never seen before.

“This was no cattle raid,” said Majak Piok, a village elder.

Southern Sudan, one of the least developed and most war-haunted parts of Africa, is at a critical point, gearing up for a vote on independence that is likely to break an already volatile Sudan in two. It is the culmination of decades of civil war and an American-backed peace treaty to end it, but as the long-savored day approaches, many south Sudanese fear another devastating war is on the horizon.