When his father, Sultan Muhammad Jamalul Alam I, died in 1804, he was still a minor followed by a physical deformity of an extra thumb on his right hand.

Pengiran Muda Omar Ali Saifuddin was supported by most nobles as he was the rightful heir according to Brunei's royal traditions.

[4] After his succession to the throne, he appointed his uncle Pengiran Muda Hashim as the Bendahara (Prime Minister) as a sign of compassion to heal their family relations after the Second Civil War.

[5] During Sultan Omar Ali Saifuddin II's reign, he tried to establish absolute control over the economic importance of Kuching.

Following Sarawak's formal transfer to him in 1847 from Omar Ali Saifuddin, Brooke extended its boundaries (from one location to another), typically at Brunei's cost.

Since Britain could exert indirect authority over new territories that were strategically and financially significant to them, they did not object at this time to private initiatives by British residents or trade corporations under their sponsorship to own towns in Northern Borneo.

[12] In July 1846, James Brooke and Admiral Sir Thomas Cochrane together began a naval attack on Brunei Town and depose the Sultan.

[13] Due to significant foreign pressure on him, towards the end on his life, Omar Ali Saifuddin's health began rapidly deteriorating.

[17] By all accounts, Sultan Omar Ali Saifuddin II was an unimpressive figure with a second thumb on his right hand and a dull mind.

He is sometimes referred to as a fool by Western observers, but it's more likely that he was simply not particularly intelligent, making him a target of plots and a tool of his advisers, whoever they happened to be at the moment.

Because the nominal leadership lacked the moral and traditional power conferred by the ceremonies involved with the complete coronation and installation, the overall impact was to weaken the government of Brunei.