[2] Raised in Fuwayrit, Qatar,[1] Jassim claimed to be descended from the Tamim tribe, as he was the eldest son of Mohammed bin Thani.

He later moved to Al Bidda with his father when he was around twenty-one years old, where he emerged among his mates as a young leader, which he later illustrated as he fended off Qatar's invaders such as the Emirate of Nejd.

[6] Jassim bin Mohammed played a significant role in the Battle of Mesaimeer, an armed conflict that occurred in Qatar from June 2-4, 1851.

Notably, Bahraini forces under Ali bin Khalifa, though nominally allied with Qatar, remained largely uninvolved in the actual fighting and later retreated.

According to local accounts, he engaged in single combat with one of Faisal's chief lieutenants, Fares Al Otaibi, ultimately defeating him.

[9] Many years after the battle, Jassim wrote a poem commemorating the battle:[10] أرى مـن صروف الدهـر ما كدر الصفا وجفـن سـهر مهـوب بالنـوم ذايـل حميـناك ـمن دوالت اإلـمام فيـصل جمـوع يقديهـا طـرى الفعايـل نطحـنا الـسبايا ـيوم ـكرت ورودـها والشـيخ فـي مثنـاة جمعـه يخايـل نطحـنا الـسبايا بالـسبايا ودـبرت ودم لعتيبـي فـوق رمحـي وشـايل I see from the vicissitudes of time what has troubled the serenity, And an eyelid, sleepless, fearful of slumber, withering.

The tribal elders appealed to Jassim bin Mohammed Al Thani for assistance, recognizing his growing influence and reputation for justice.

This action resulted in the expulsion of the Bahraini deputy amir, Ahmed bin Mohammed Al Khalifa, who fled by sea to northern Qatar.

[12] Bahrain succeeded in gaining support from Abu Dhabi, as Doha and Al Wakrah have long been harbors of refuge for Omani seceders, to launch attacks on major Qatari cities in what became known as the Qatari–Bahraini War, causing significant damage.

In retaliation, Qatar attacked Bahrain in 1868 in what was known as the Battle of Al Damsah, resulting in the deaths of a thousand men and the sinking of sixty ships.

[13] The aftermath of the Battle of Damsah saw the Qatari forces execute a strategic withdrawal, prompting a pursuit by Bahraini troops to the settlement of Al Wakrah.

He wrote to the new ruler of Bahrain, Isa bin Ali, promising to pay him a ransom for Muhammad's release: a thousand of the finest camels and ninety of the noblest horses.

فـــال يــا عيــال العــم فكــوا محمـــد مــن الحبــس ال ترضــون لــه بــذالل فعندي لكم من الخيل تسعين سابق وألـف مـن الهجـن النجـاب اجالل علــ ّّي يمـــين اللــه إنـــي أســوقـــها لعــــل عـــــثرات الكــريم ُت O cousins, release Mohammed from prison Do not be content with his humiliation I have for you ninety racing horses And a thousand of the finest, purebred camels I swear by God that I will drive them Perhaps the stumbles of the noble will be forgiven In April 1871, the expedition sent by Midhat Pasha, the Ottoman governor of Baghdad, to Eastern Arabia arrived.

In January 1872, Qatar was formally incorporated into the Ottoman Empire as a province in Najd with Sheikh Jassim being appointed its kaymakam (sub-governor).

He renounced his jurisdiction of Doha the same year, and members of the Bani Hajir tribe attacked the pearl traders shortly after, resulting in the merchants' withdrawal from the country and the forfeiture of their profits during that period.

[21] During Jassim bin Mohammed Al Thani's rule, Qatar experienced significant tensions with the neighboring Emirate of Abu Dhabi, rooted in long-standing territorial disputes and tribal rivalries along their shared border and exacerbated by the complex interplay of Ottoman and British imperial interests in the Gulf region.

[23] In 1887, Jassim led an expedition into Khor Al Adaid in southern Qatar, accompanied by Ottoman troops, to assert his claim over the disputed territory.

In April 1889, Sheikh Zayed bin Khalifa Al Nahyan of Abu Dhabi, assisted by the rulers of Dubai and Muscat and Oman, launched a retaliatory offensive along the Qatari Peninsula and Al-Ahsa, but withdrew after warnings from Ottoman representatives in Qatar.

In March, after a month of back-and-forth parleying, Mehmed lost patience and imprisoned Sheikh Jassim's brother and between 13 and 16 prominent Qatari tribal leaders on the Ottoman corvette Merrikh.

[32] He died on the afternoon of 17 July 1913 and was buried in Lusail, a village located 24 km north of Doha, which is found in the municipality of Al Daayen.