The al-Rahman Legion was part of the Unified Military Command of Eastern Ghouta, established in 2014, along with Jaysh al-Islam (led by Zahran Alloush) and Ahrar al-Sham.

[24] Al-Rahman Legion and Jaysh al-Islam were allied in the Rif Dimashq offensive (September 2015), or the battle of "Allah al-Ghalib", around Tall Kurdi, Adra, and Harasta in Eastern Ghouta.

[31] From 18 April until 24 May 2016, the Legion was involved in heavy clashes with rival rebel faction Jaysh al-Islam, while also fighting against government forces in the Rif Dimashq offensive (April–May 2016).

On 26 April 2016, the 1st Brigade of Damascus (then an FSA-affiliated group armed with BGM-71 TOW missiles) left the Southern Front and joined the Legion.

[35][36][better source needed] On 24 May 2016, leaders of Jaysh al-Islam and al-Rahman Legion met to sign a Qatari-backed deal to end hostilities after the East Ghouta inter-rebel conflict (April–May 2016), supervised by Riyad Farid Hijab.

On 14 June 2016, clashes erupted again, with the al-Rahman Legion taking control of several zones previously held by Jaysh al-Islam in the southern part of Eastern Ghouta.

Previously several of these groups have seceded in order to join the Ajnad al-Sham Islamic Union and the now defunct Jaysh al-Ummah.

[40] From April 2017, heavy clashes restarted between Jaysh al-Islam and the Rahman Legion, backed by Tahrir al-Sham (HTS).

In February 2018, government forces launched a large-scale offensive to recapture eastern Ghouta from rebel groups, including the Rahman Legion.

[51] On 23 March, the Legion reached a surrender agreement with Russia, and began to evacuate its fighters and their families from Zamalka, Arbin, Ein Tarma, and Jobar the next day.