Heglig - called Panthou in Dinka - lies in the contested area between Sudan and newly independent South Sudan. The 2005 Comprehensive Peace Agreement had deferred the question of exactly where the border ran through this petroleum-rich zone, and the Permanent Court of Arbitration's 2009 ruling on Abyei had not resolved the surrounding fields. By early 2012, relations between Khartoum and Juba had broken down over transit fees for southern oil moving through Sudan's pipelines. Both sides accused the other of cross-border attacks. South Sudan claimed that Sudan had been harassing its forces with artillery and airstrikes. On 10 April 2012, citing retaliation, the Sudan People's Liberation Army launched an offensive north into the Heglig area. The SPLA said they were pursuing retreating Sudanese units. Within a day, after fierce clashes, Sudan's army admitted defeat - briefly conceding that South Sudanese forces had overrun their positions despite what Khartoum described as stiff resistance against "Huge, well equipped forces" from the south.

By 13 April, South Sudanese forces had reinforced their positions in Heglig while Sudan mobilized for a counteroffensive. Both sides issued dueling statements - the SPLA saying they would defend what they held, the Sudanese government spokesman saying the situation would be "dealt with within hours." On 15 April, Sudanese warplanes bombed Heglig, with Southern officials accusing Khartoum of reducing the central processing facility to rubble. Sudan denied it. Neither claim could be fully verified from the outside, because international journalists mostly could not reach the front lines, and both governments were issuing selective accounts. On 20 April, Sudanese forces entered Heglig and re-established control of the oilfield. The oil facilities themselves were damaged. The oil production schedule that both countries depended on - Sudan for pipeline revenue, South Sudan for oil that had to move through those pipelines - was badly disrupted.

The Sudanese army claimed to have killed over 1,000 South Sudanese soldiers at Heglig. The actual number is impossible to verify with any confidence. What is not disputed is what an AFP correspondent who reached Heglig after Sudan's recapture saw: the bodies of South Sudanese soldiers lying beneath trees scattered across the area. There were too many to count, too many to bury. The corpses wore the flag of the country they had been born into less than a year before. Earlier in the occupation, a Southern soldier in Bentiu, the capital of Unity State, had told reporters: "There are so many bodies at the front line, so many dead." It was impossible to bury them all, or bring them home. South Sudan denied the scale of its losses publicly, for reasons of morale and international positioning. But the men who were killed had names their mothers knew, and the hills above Heglig kept the record of how many had fallen there.

The Second Battle of Heglig was formally part of the wider Heglig Crisis, a short war that threatened to become a much larger one. United Nations Security Council Resolution 2046, passed on 2 May 2012, demanded that both countries cease hostilities and resume negotiations. Sudan and South Sudan eventually did - the September 2012 Cooperation Agreement addressed oil transit fees and border management, though it left the core question of Heglig's sovereignty unresolved. The oilfields, recovered by Sudan, kept producing for Khartoum. The South Sudanese soldiers who had died trying to take them were never really counted. The border communities on both sides - Nuba, Ngok Dinka, Missriya, Southern Kordofani Arabs, Unity State Nuer - kept trying to live their lives astride a line that armies kept fighting over. Nine months into independence, South Sudan learned that sovereignty on paper did not translate to sovereignty on ground when oil was involved.