[2] He tried to appease the previous Sultan's followers by appointing Muhammad Ali's grandson, Muhyiddin as the new Bendahara ("Chief Minister").

[2] After a while, however, Muhammad Ali's supporters took revenge by convincing Bendahara Muhyiddin to stand up against Abdul Hakkul Mubin.

[2] Sultan Abdul Hakkul Mubin then moved his palace to Chermin Island under the advice of Muhyiddin with the intent to wait the crisis out.

[2][3][4][5] During the civil war, Abdul Hakkul Mubin fled to Kinarut (in present-day Papar, Sabah, Malaysia) where, he stayed there for ten years, repelling repeated attacks by Sultan Muhyiddin.

[2] They returned to Brunei after a final attack by Muhyiddin's forces in which they failed to defeat Abdul Hakkul Mubin.

Muhyiddin eventually emerged victorious in the civil war and Abdul Hakkul Mubin was killed and later buried at the royal burial ground on the island.