He consequently rose in the ranks of the PLO, and became an important military commander in the Arab–Israeli conflict, taking part in missions in Lebanon, Yemen, Sudan, and Uganda.

Following the Oslo I Accord, Da'as became President Yasser Arafat's personal military advisor and a deputy in the Palestinian Legislative Council.

Mahmoud Da'as was born to ethnic Palestinian parents in Hajjah, a village located in the Qalqilya District of Mandatory Palestine.

[2][3] Soon after his birth, his family relocated to the Jordianian city of al-Karak, where his father found work as policeman in the British-led security forces.

[5] When the Uganda–Tanzania War broke out in 1978, the Uganda Army quickly proved incapable in the face of the Tanzania People's Defence Force (TPDF), and Amin's regime began to collapse.

The PLO high command was alarmed, fearing that the end of Amin's government would result in the ouster of the Palestinian militants from Uganda.

[6] The Tanzanians began their attack on Kampala on 10 April 1979, and the PLO troops under Da'as reportedly resisted some time before retreating northward.

In course of this conflict, Da'as served as Director of Officer Affairs and Fortifications and took part in the fighting against the Israel Defense Forces, including during the Siege of Beirut.

As result of the Oslo I Accord, Da'as and the rest of the PLO leadership was able to return to Palestine in 1994, and he became a candidate in the 1996 Palestinian general election.

[2] President Yasser Arafat made him his military advisor and a member of Palestine's Supreme National Security Council.