1984
August: The ONLF formed as a splinter group from the Western Somalia Liberation Front. There was violence throughout the region after Britain recognized Ethiopia's claim to the Ogaden territory in 1954. Since 1984, the ONLF has maintained a significant presence in the Ogaden-Somali region, largely focused on independence from Ethiopia.
2000
The ONLF and OLF joined with four other groups to form the United Liberation Front of Oromiya, a nominal entity. Attacks continued to be unilaterally claimed by the ONLF.
2004
June: ONLF promised to suspend its violent campaign in the Ogaden. Nonetheless, its attacks on Ethiopian government troops continued.
2005
A second peace effort failed in mid-year and ONLF resumed overt insurgent activities.
November: The ONLF claimed responsibility for attacks that resulted in the deaths of 34 government troops and the capture or destruction of several vehicles. The government reported the deaths of several ONLF prisoners who were said to be trying to escape from prison.
2006
May: The ONLF joined several political parties to form the AFD, a coalition seeking to address the conflict in the Ogaden region through consultations with the EPRDF.
August: The Ethiopian government conducted a major operation designed to clear separatist rebels from the region after attempts to hold talks bogged down. Ethiopian security forces killed 13 members of the ONLF and captured several commanders as they crossed into Ethiopia from Somalia.
Aug. 28: Mahdi Ayuub, the former head of the regional security bureau, was arrested in Jigjiga, Ethiopia.
September: The International Committee of the Red Cross suspended its operations in eastern Ethiopia after two of its aid workers were kidnapped by armed gunmen in the disputed region. The Ethiopian government said the incident took place in an area where the ONLF was known to be active.
November: Tribal chiefs urged the ONLF militia group to refrain from terrorist activities and to seek peaceful mediation.
November: A Swedish oil company announced its intention to develop petroleum resources in the region. The Ogaden province has turned out to be Ethiopia's most promising region in terms of mineral resources, and international oil companies are optimistic about finding commercially productive reserves there. The ONLF warned the Swedish company against making any deals in the region.
October: The ONLF accused the Ethiopian government of grossly misrepresenting the facts about the possible negotiations. According to the ONLF, these talks never materialized because the Ethiopian government refused to hold them in a third country with independent mediators and without preconditions.
2007
March: ONLF condemned what it called the deliberate torching of a village in the Ogaden by Ethiopian troops, terming it state-sponsored terrorism.
April 24: ONLF fighters attacked Chinese oilfield facilities near the town of Abole in the Ogaden region, killing nine Chinese oil workers and 68 Ethiopians. Seven other Chinese were abducted and later released to the Red Cross. "Oil investments in Ogaden will result in a similar loss for any firm that believes assurances of security it receives from the Ethiopian government, which has never been in effective control of Ogaden," said an ONLF statement.
May 28: An ONLF grenade attack on a cultural gathering in Jijiga killed four middle school students.
May 28: Fifty civilians were wounded and three were killed in an ONLF attack.
July 1: An attack on the town of Dobaweyn in Korahey region attributed to ONLF left 10 civilians dead.
Sept. 20: ONLF members attacked the town of Shilabo, leaving five civilians dead.
Sept. 21, 2007: An ONLF-planted land mine near Aware in Dagahbour region exploded, killing three civilians in a passing vehicle.
Sept. 25, 2007: The group was blamed for an attack on a vehicle near El-Har, just outside of Kebridahare, which killed two civilians.
Sept. 27, 2007: An ONLF unit attacked the district of Lahelow near the Ethiopia-Somalia border, targeting members of the Isma'il Gum'adle sub-clan, killing 12.
2008
January: An Ethiopian security official said that ONLF had killed 200 civilians from November 2007 to January 2008.
May 21: Ethiopian Prime Minister Meles Zenawi said that the ONLF had been largely "neutralized" by the military offensive that began in 2007. Zenawi contended that the ONLF, as an organized group, was no longer operating, although he conceded that a few ONLF individuals remained active. The ONLF denied that it had been defeated.
2009
Jan. 18: Security forces killed former ONLF leader Mohammed Serad Dolal in Denan, Ethiopia. The Somali government reported that other members of the ONLF leadership and the Al- Ittihad group were also killed during a security operation in the region. Mohammed Serad was said to have left Eritrea and joined the Al-Ittihad terrorist group after ONLF's presence deteriorated. ONLF had no armed forces left in the state and that its political existence was fragile, said the government. Mohammed Serad had reportedly been in a leadership struggle with Mohamed Omar Osman, causing a split in the organization and the creation of a breakaway ONLF group led by Salahdin Abdurahman Maow.
February: Both government and rebel sources reported that at least 45 persons were killed in a clash between the ONLF and the Ethiopian military near the towns of Fik and Degehebur.
March 9: ONLF claimed it had seized control of the town of Mustahil and was fighting for control of two others. The group said at least 80 Ethiopian soldiers had been killed. The Ethiopian government denied the ONLF report and said that the rebel group was in retreat.
June: ONLF fighters attacked an Ethiopian road construction team, burning five vehicles and kidnapping 18 workers; 13 were later released.
July: Police and ONLF fighters clashed in the towns of Degehabur and Kabsidakas. Up to 65 police were killed, as were two suspected ONLF members were killed at the Degehabur town market.
Sept. 16: ONLF issued warnings to companies against exploring for oil in the Ogaden region. Businesses should avoid activities in the region "until there is a political solution to the conflict," the ONLF said, adding that it would not be responsible for any collateral damage. The group maintains that the oil companies have stolen natural resources of the local people.
Oct. 19: Ethiopia claimed it had essentially defeated the Ogaden National Liberation Front. Remnants of the group, however, were still conducting sporadic attacks on Ethiopian security forces. Restrictions on both the media and aid workers have created difficulties in assessing conditions in the Ogaden. The Internal Displacement Monitoring Center (IDMC) said hundreds of thousands had been displaced.
Nov 16: Ethiopia disputed claims that ONLF had seized seven towns near the border with neighboring Somalia. The group said it had it had taken the towns after almost a week of fierce fighting with the Ethiopian army. The government called the attacks "the desperate act of a dying force" and said that about 245 ONLF fighters had been killed.
Nov 10: The ONLF claimed that 985 government soldiers were killed in a clash with the militants.
2010
May 30: Ethiopia denied ONLF's claim that it had taken control of a gas field in the Ogaden region. The government reiterated its claim that the ONLF was in disarray.
June 25: About half of ONLF's forces had agreed to a peace plan after talks in Germany, said Ethiopia. The ONLF reportedly agreed to abide by the country's constitution and the leaders and their forces had been granted amnesty. said the goal was to get an agreement within three months. The government estimated that ONLF had only 250 active fighters before the group split roughly in half, with the more militant faction remaining affiliated with Eritrea. The ONLF issued a statement that no agreement had been reached and called the government report a "blatant lie."