It consisted of a series of incidents along the then-disputed border; including the Eritrean–Ethiopian War of 1998–2000 and the subsequent Second Afar insurgency.

This led to the Eritrea–Ethiopia summit on 9 July 2018, where an agreement was signed which demarcated the border and agreed a resumption of diplomatic relations.

[12] In 1884, the Hewett Treaty was signed between the British Empire and Ethiopia, ruled by Emperor Yohannes IV (r. 1871–1889).

The British Empire promised the highlands of modern Eritrea—and free access to the Massawan coast to Ethiopia in exchange for its help evacuating garrisons from the Sudan, in the then-ongoing Mahdist War.

[13] In 1889, amid the disorder that followed the death of Yohannes IV, Italian General Oreste Baratieri occupied the highlands along the Eritrean coast and Italy proclaimed the establishment of a new colony of "Eritrea", (from the Latin name for the Red Sea), with its capital at Asmara in substitution for Massawa.

Unusually, the Italians retained most, if not all, of the territories beyond the Mareb-Belessa and May/Muni rivers that they had taken, with Emperor Menelik II (r. 1889–1913) giving away part of Tigray.

[27] By 3 October 1935, the Italian Army led by General Emilio De Bono launched an invasion of Ethiopia, without a declaration of war.

However thousands of Italian soldiers began conducting a guerrilla war within their former colony[33] which lasted until October 1943.

The Soviet Union similarly wished to make it their trustee; and tried, unsuccessfully, to achieve this by diplomatic means.

It engaged in clandestine political activities intended to cultivate resistance to the centralising policies of the imperial Ethiopian state.

[39] During the following decade the Emperor decided to dissolve the federation between Ethiopia and Eritrea, annexing the special region and bringing it under direct rule.

[42] On 12 September 1974, a successful coup d'état was carried out against the Emperor led by Lieutenant General Aman Andom.

[50] On 13 May 1998, Eritrean radio described the incidents as a "total war" policy from Ethiopia, and claimed that the Ethiopian Army was mobilising for a full assault against Eritrea.

It was patrolled by the United Nations Mission in Ethiopia and Eritrea (UNMEE) an organisation for the border stabilisation and the prevention of future conflicts between the countries.

[71] Then, on 15 December the United Nations began to withdraw peacekeepers from Eritrea in response to a UN resolution passed the previous day.

[72] On 21 December 2005, a commission at the Permanent Court of Arbitration in The Hague ruled that Eritrea broke international law when it attacked Ethiopia in 1998, triggering the broader conflict.

[73] Ethiopia and Eritrea subsequently remobilized troops along the border, leading to fears that the two countries could return to war.

[74][75] On 7 December 2005, Eritrea banned UN helicopter flights and ordered Western members (particularly from the United States, Canada, Europe and Russia) of the UN peacekeeping mission on its border with Ethiopia to leave within 10 days, sparking concerns of further conflict with its neighbour.

[76] In November 2006 Ethiopia and Eritrea boycotted an Eritrea–Ethiopia Boundary Commission meeting at The Hague which would have demarcated their disputed border using UN maps.

[77] In September 2007, Kjell Bondevik, a United Nations' official, warned that the border conflict could cause a new war.

Many feared the weak Eritrean economy is not improving like those of other African nations, while others say Ethiopia was still bogged down in its intervention in Somalia.

[80] In February, the UNMEE commenced pulling its peacekeepers out of Eritrea due to Eritrean Government restrictions on its fuel supplies.

[86] On 5 June 2018 Ahmed announced that Ethiopia relinquished its claims on the disputed areas and that the conflict with Eritrea was at an end.

John Young, a Canadian analyst and researcher for IRIN, the United Nations Office for the Coordination of Humanitarian Affairs news agency, reported that "the military victory of the EPRDF (Ethiopia) that ended the Ethiopia–Eritrea War, and its occupation of a swath of Eritrean territory, brought yet another change to the configuration of armed groups in the borderlands between Ethiopia and Eritrea.

Asmara replaced Khartoum as the leading supporter of anti-EPRDF armed groups operating along the frontier".

[98] Soon after the peace summit, many Ethiopian rebels returned to Ethiopia, including TPDM, OLF and Ginbot 7.

On 19 June 2008 the BBC published a time line (which they update periodically) of the conflict and reported that the "Border dispute rumbles on":* 2007 September – War could resume between Ethiopia and Eritrea over their border conflict, warns United Nations special envoy to the Horn of Africa, Kjell Magne Bondevik.

[116] In July, a United Nations Monitoring Group accused Eritrea of being behind a plot to attack an African Union summit in Addis Ababa, the capital of Ethiopia, in January 2011.

[117] In January 2012, five European tourists were killed and another two were kidnapped close to the border with Eritrea in the remote Afar Region in Ethiopia.