Shekau's death was regarded as a major event by outside observers, as he had been one of the main driving forces in the Islamist insurgency in Nigeria and neighboring countries since 2009.

Its de facto leader Abubakar Shekau consequently attempted to increase his international standing among Islamists by allying with the prominent Islamic State (IS).

[3][4] When the insurgents were subsequently defeated and lost almost all of their lands during the 2015 West African offensive by the Multinational Joint Task Force (MJTF), discontent grew among the rebels.

[3][4][5] Despite orders by the IS central command to stop using women and children suicide bombers as well as refrain from mass murdering civilians, Shekau refused to change his tactics.

[6] Researcher Aymenn Jawad Al-Tamimi summarized that the Boko Haram leader proved to be "too extreme even by the Islamic State's standards".

They began using suicide vehicle-borne improvised explosive devices[10] and drones which experts considered proofs of support and advice by exiled IS members from Syria and Iraq.

[10][11] ISWAP also focused on military targets and attempted to win the support of the local civilians, unlike Shekau whose forces were notorious for massacring and kidnapping non-combatants.

[6] The Islamic State employed a "hearts and minds" policy toward the local communities, gradually winning substantial grassroots support,[12] and implemented its own government, including collecting taxes.

[16] Al-Naba, the Islamic State's official newspaper, later claimed that Shekau's activities had disrupted local communities to such a degree that famine had become a major issue, allegedly making an intervention of ISWAP necessary.

[18] In addition, the Islamic State faction deviated from Shekau's brutal and autocratic leadership style by organizing a powerful shura or committee that gave the group an element of "democracy".

[24] Around this time, dissatisfaction within Boko Haram reportedly rose due to Shekau executing his chief of staff Abu Fatima.

[23] Al-Naba also vaguely stated in an article that ISWAP had been ordered to eliminate Shekau, hinting that the IS central leadership had been involved in the decision making process.

[17] Conspiracy theories circulated which alleged that non-Jihadist outside powers had been involved in the escalation of the inter-rebel conflict, arguing that it was part of a wider rivalry between "Anglophone Nigeria and its Francophone neighbors".

[17] While al-Barnawi acted as ISWAP chief commander, Muhammad Dawud (alias "Abu Hafsat") coordinated the offensive alongside Islamic State officers of the Lake Chad area, Timbuktu triangle[a] and Marte.

[17] Using motorcycles[25] and dozens of technicals outfitted with heavy weapons, ISWAP chased the Boko Haram troops outside the bases, killing many[6][22] and convincing more to surrender.

ISWAP spent the next day securing the captured areas, continuing to search for Shekau, and patrolling through the forest with voice amplifiers announcing its aims and requesting Boko Haram stragglers to surrender.

[30] According to HumAngle, a website "run by well-informed Nigerian reporters",[12] Shekau and his remaining followers attempted to flee from a temporary camp on late 19 May 2021,[15] but were encircled by ISWAP[6] troops led by Dana Daguri.

[22] Bako Gorgore and another ISWAP officer reportedly approached him, and implored the Boko Haram leader as well as his aides to remove their suicide vests.

[15] Analyst Ahmad Salkida argued that ISWAP wanted Shekau alive, as only he could convince his remaining followers to voluntarily join the Islamic State forces.

[28] About 30 Boko Haram commanders were reportedly captured[25] including Mustapha Krimima Jaysh, Ba'akaka, Malkin Tijjani, Hirasama, and Mallam Ballu.

Journalist John Owen Nwachukwu argued that Shekau had usually appeared in videos or audio messages directly after claims of his death had circulated.

[14][36] Analyst Bulama Bukarti argued that "Shekau's death will be a huge turning point", as it could either worsen the fighting between the Boko Haram remnants and ISWAP or result in the merger of the former into the latter and the reunification of the insurgents.

Jason Burke commented that the Islamic State had managed "something Nigerian forces, despite the dispatch of multinational taskforces put together by western governments and vast sums of aid, had been unable to do in 12 years of fighting".

[7] With Sambisa Forest under its control, ISWAP reportedly holds a large area in Borno State and has created a chain of strongholds from Nigeria to Mali to southern Libya.

[32] The Boko Haram remnants were reportedly consolidating under Bakura Sahalaba[36] who had begun to launch counter-attacks on ISWAP targets in the Lake Chad area, prompting al-Barnawi to implore Shekau's former followers to lay down arms and join the Islamic State.

[35] Bakura Sahalaba later released a video in which he condemned ISWAP for being responsible for Shekau's death, and reaffirmed that Boko Haram would continue to fight.

[38] Some Boko Haram members who initially joined ISWAP after Shekau's death, such as a faction led by four commanders of the Njimiya camp, later rebelled again and waged a low-level anti-IS guerrilla campaign in Sambisa Forest.