Abu Ishaq was born to a Turkic mother who was a concubine of his father, caliph Harun al-Rashid. Muhammad ibn Jarir al-Tabari records that Abu Ishaq led the pilgrimage in A.H. 200 (815-816) and in 201. Al-Tabari mentions that in 202 Abu Ishaq commanded a force sent against some Kharijite rebels. One of the happenings on this campaign was that one day in combat one of the Turkish military clients ghilman there advanced in between a Kharijite lancer and the future caliph. The Turk shouted, "Recognize me!" (In Persian "Ashinas ma-ra.") To express his appreciation, Abu Ishaq on that same day granted this man the name Ashinas and he became known as Abu Ja'far Ashinas. Abu Ishaq defeated these Kharijites.
In A.H. 214 (829-830) Abu Ishaq subdued Egypt and executed some leading rebels. He returned in 215 to join al-Ma'mun in a campaign against the Byzantines. Abu Ishaq commanded forces that captured thirty Byzantine strongholds.
Al-Tabari records that al-Mu'tasim was hailed caliph on August 9, 833. He promptly ordered the dismantling of al-Ma'mun's military base at Tyana. He sent Ishaq ibn Ibrahim ibn Mu'sab against a Khurramiyyah revolt centred near Hamadhan. Ishaq soundly defeated the rebels. Their survivors fled to the Byzantines.
In A.H. 219 (834-835) Muhammad ibn al-Qasim rebelled in Khurasan. He was defeated and brought to the caliph. He was imprisoned, but escaped and was never heard of again. Ujayf ibn Anbasah defeated the Zutt in Iraq. The next year he brought them before al-Mu'tasim in an impressive naval parade. The Zutt were sent to the Byzantine frontier where they fell fighting Byzantines.
One of the most difficult problems facing this Caliph, as faced his predecessor, was the uprising of Babak Khorramdin. Babak first rebelled in A.H. 201 (816-817) and overcame a number of caliphate forces sent against him. Finally, al-Mu'tasim provided clear instructions to his general al-Afshin Khaydhar ibn Kawus. Following these al-Afshin patiently overcame the rebel, securing a significant victory of this reign. Babak was brought to Samarra in A.H. 223 (837-838). He entered the city spectacularly riding on a splendid elephant. He was executed by his own executioner and his head sent to Khurasan. His brother was executed in Baghdad.
In that same year of Babak's death, the Byzantine emperor Theophilus launched an attack against a number of Abbasid fortresses. Al-Mu'tasim launched a well planned response. Al-Afshin met and defeated Theophilus on July 21, 838. Ankyra fell to the Muslim army of 50,000 men (with 50,000 camels and 20,000 mules) and from there they advanced on the stronghold of Amorium. A captive escaped and informed the caliph that one section of Amorium's wall was only a frontal facade. By concentrating bombardment here, al-Mu'tasim captured the city.
On his return home, he became aware of a serious conspiracy centred on al-Abbas ibn al-Ma'mun. A number of senior military commanders were involved. Al-Abbas was executed, as were, among others, al-Shah ibn Sahl, Amr al-Farghana, Ujayf ibn Anbasah and Akhmad ibn al-Khalil. This situation may help explain the increased reliance of this caliph and his successors upon Turkish commanders.
The ghilman (sing. ghulam) were introduced to the Caliphate during al-Mu'tasim's reign. The ghilman were slave-soldiers taken as prisoners of war from conquered regions, in anticipation of the Mamluk system, and made into caliphal guard. The ghilman, personally responsible only to the Caliph, were to revolt several times during the 860's, killed 4 caliphs, and be replaced by the Mamluk system, based on captured Turkish children, trained and moulded within the Islamic lands.
The ghilman, along with the shakiriya which had been introduced in the reign of al-Ma'mun, had irritated the Arab regular soldiers of the Caliph's army. The Turkic and Armenian ghilman agitated the citizens of Baghdad, provoking riots in 836. The capital was moved to the new city of Samarra later that year, where it would remain until 892 when it was returned to Baghdad by al-Mu'tamid.
The Tahirid dynasty, which had come to prominence during al-Ma'mun's reign after the military province of Khurasan was granted to Tahir bin Husain, continued to grow in power. They received the governorships of Samarqand, Farghana, and Herat. Unlike most provinces in the Abbasid Caliphate, which were closely governed by Baghdad and Samarra, the provinces under the control of the Tahirids were exempted from many tributes and oversight functions. The independence of the Tahirids contributed greatly to the decline of Abbasid supremacy in the east.
In A.H. 224 (838-839) Mazyar ibn Qarin who detested the Tahirids rebelled against them. Previously, he had insisted on paying the taxes of his Caspian region directly to al-Mu'tasim's agent instead of to Abdallah ibn Tahir's. Al-Afshin, desiring to replace Abdallah as Khurasan's governor, intrigued with Mazyar. Mazyar imprisoned people from Sariya, demolished Amul's walls and fortified Tamis, causing apprehension in Jurjan.
Abdallah and al-Mu'tasim despatched forces to quell this uprising. Abdallah's commander Hayyan ibn Jabalah convinced Mazyar's Qarin ibn Shahriyar to betray Mazyar. Qarin sent Hayyan Mazyar's brother and other commanders Qarin had taken by surprise. The people of Sariyah rose against Mazyar. Hayyan arrived there and then advanced into the Wandahurmuz mountains where he seized some of Mazyar's stored wealth. Al-Quhyar ibn Qarin betrayed Mazyar. He was brought, along with his correspondence, some implicating al-Afshin, to al-Mu'tasim. Mazyar's commander al-Durri was defeated, captured and executed.
Al-Hasan ibn al-Afshin had a splendid wedding celebration with al-Mu'tasim personally providing for the guests. Al-Afshin's kinsman Minkajur rebelled in Adharbayjan. He was quickly defeated. Al-Afshin fell under suspicion. When Mazyar entered Samarra on a mule, al-Afshin was arrested. Al-Afshin was intently interrogated. Mazyar supplied testimony against him. He faced further charges of diverting wealth from the Babak campaign to al-Afshin's realm of Ushrusanah, of having idolotrous books, etc., of being addressed in Persian by his correspondents as "Lord of Lords," etc. Although al-Afshin tried to explain such things, al-Mu'tasim had him imprisoned in a special prison built for him. Here he was killed in May or June of 841.
The Khurramiyyah were never fully suppressed, although they slowly vanished during the reigns of succeeding Caliphs. Near the end of al-Mu'tasim's life there was an uprising in Palestine. Al-Mu'tasim sent Raja ibn Ayyub al-Hidari to restore order. Al-Hidari defeated the rebels and captured their leader Abu Harb al-Mubarqa.
The great Arab mathematician al-Kindi was employed by al-Mu'tasim, and tutored the Caliph's son. al-Kindi had served at the Bayt al-Hikma, or House of Wisdom. He continued his studies in Greek geometry and algebra under the caliph's patronage.
Ideologically, al-Mu'tasim followed the footstep of his half-brother al-Ma'mun. He continued his predecessors support for heretical (alleged) islamic sect of Mu'tazila, applying his brutal military methods for torturing Imam Ahmad ibn Hanbal.
Sulaymaan said, ‘He was then carried to the prison and the people departed, so I departed with them. Then when the next day arrived the people came (to the door of al-Mu’tasim) so I came with them and stood in front of the chair. Then al-Mu’tasim appeared and sat on the chair and said, ‘Bring Ahmad ibn Hanbal.’ So he was brought and when he stood in front of him al-Mu’tasim said to him, ‘How were you in your cell during the night, 0 son of Hanbal?’ He said, “In goodness, and all praises are due to Allaah.” Al-Mu‘tasim said, ‘0 Ahmad, I saw a dream yesterday.’ He said, “And what did you see, 0 Ameerul-Mu’mineen?” He said, ‘I saw in my dream as if there were two lions approaching me and they desired to tear me apart. And then two angels appeared and repelled them from me. They gave me a hook and said to me, ‘This written (piece) is the dream that Ahmad ibn Hanbal saw in his cell.’ So what is it that you saw, 0 son of Hanbal?’ So Ahmad faced al-Mu’tasim and said, “0 Ameerul-Mu’mineen, is the book with you?” He said, ‘Yes, and when I awoke, I read what was in it. So Ahmad said to him, “0 Ameerul-Mu’mineen, I saw as if the Day of Judgement had been established, and as if Allaah had gathered the first and the last (of people) in a single plain and He was calling them to account. Whilst I was standing, I was called for, so I proceeded until I stood in front of Allaah, the Mighty and Majestic, and He said to me, ‘0 Ahmad, for what were you beaten?’ I said, “On account of the Qur’aan.” He said, “And what is the Qur’aan?” I said, “Your words, 0 Allaah, belonging to You.” He said, ‘From where do you (derive and) say this?’ I said, “0 Lord, ‘Abdur-Razzaaq narrated to me.” So ‘AbdurRazzaaq was called for and he was brought, until he was made to stand in front of Allaah, the Mighty and Magnificent, and He said to him, ‘What do you say about the Qur’aan, 0 ‘Abdur-Razzaaq?’ He said, ‘Your words, 0 Allaah, belonging to You,’ so Allaah said, ‘From where do you (derive and) say this?’ He said, ‘Ma’mar narrated to me.’ So Ma’mar was called for and he was brought, until he was made to stand in front of Allaah, the Mighty and Magnificent, and He said to him, ‘What do you say about the Qur’aan, 0 Ma’mar?’ He said, ‘Your words, 0 Allaah, belonging to You,’ so Allaah said, ‘From where do you (derive and) say this?’ He said, ‘Az-- Zuhree narrated to me.’ So az-Zuhree was called for and he was Brought, until he was made to stand in front of Allaah, the Mighty and Magnificent, and He said to him, ‘What do you say about the Qur’aan, 0 Zuhree?’ He said, ‘Your words, 0 Allaah, belonging to You,’ So Allaah said, ‘From where do you (derive and) say this?’ He said, “Urwah narrated to me.’ So ‘Urwah was brought, and He said to him, ‘What do you say about the Qur’aan?’ He said, ‘Your Words, 0 AIIaah, belonging to You,’ so Allaah said, ‘0 ‘Urwah, from where do you (derive and) say this?’ He said, “Aa’ishah, the daughter of Aboo Bakr as-Siddeeq, narrated to me.’ So ‘Aa’ishah was called for and she was brought, until she was made to stand in front of Allaah, the Mighty and Magnificent, and He said to her, ‘What do you say about the Qur’aan, 0 ‘Aa’ishah?’ She said, ‘Your words, 0 Allaah, belonging to You,’ so Allaah said, ‘From where do you (derive and) say this?’ She said, ‘Your Prophet Muhammad (swallallahu alaihi wasallam) narrated to me.’ He said, ‘So Muhammad (swallallahu alaihi wasallam) was called for and he was brought, until he was made to stand in front of Allaah, the Mighty and Magnificent, and He said to him, ‘What do you say about the Qur’aan, 0 Muhammad?’ He said, ‘Your words, 0 Allaah, belonging to You,’ so Allaah said, ‘From where has this come to you?’ So the Prophet (swallallahu alaihi wasallam) said, ‘Jibreel narrated to me.’ So Jibreel was called for and he was brought, until he was made to stand in front of Allaah, the Mighty and Magnificent, and He said to him, ‘What do you say about the Qur’aan, 0 Jibreel?’ He said, ‘Your words, 0 Allaah belonging to You,’ so Allaah said, ‘From where has this come to you?’ He said, ‘Such did Israafeel narrate to me. So Israafeel was called for and he was brought, until he was made to stand in front of Allaah, the Mighty and Magnificent, and Allaah, the Sublime, said to him, ‘What do you say about the Qur’aan, 0 Israafeel?’ He said, ‘Your words, 0 Allaah, belonging to You,’ so Allaah said, ‘From where has this come to you?’ He said, ‘I saw that in the Lawhul-Mahfooz (the Preserved Tablet).’ So the Preserved Tablet was brought and stood in front of Allaah, the Mighty and Magnificent, and He said, ‘0 Lawh, what do you say about the Qur’aan?’ And it said, ‘Your words, 0 Allaah, belonging to You.’ Then Allaah, the Exalted said, ‘From where has this come to you?’ And the Lawh said, ‘Such did the Qalam (the Pen) inscribe upon me.’ Then the Pen was brought until it stood in front of Allaah, the Mighty and Majestic, so Allaah, the Mighty and Majestic, said to it, ‘0 Qalam, what do you say about the Qur’aan?’ The Qalam said, ‘Your words, 0 Allaah, belonging to You.’ So Allaah said, ‘From where has this come to you?’ The Qalam said — ‘You dictated and I wrote.’ Then Allaah, the Mighty and Magnificent, said, ‘The Qalam has spoken the truth. The Lawh has spoken the truth. Israafeel has spoken the truth. Jibreel has spoken the truth. Muhammad has spoken the truth. ‘Aa’ishah has spoken the truth. ‘Urwah has spoken the truth. Az-Zuhree has spoken the truth. Ma’mar has spoken the truth. ‘Abdur-Razzaaq has spoken the truth. Ahmad ibn Hanbal has spoken the truth. The Qur’aan is My Speech, it is not created.’
Sulaymaan as-Sijzee said, ‘Al-Mu’tasim leapt upon hearing that and said, ‘You have spoken the truth, 0 son of Hanbal.’ Then al- Mu’tasim repented, ordered the necks of Bishr al-Mareesee and Ibn Abee Duwaad to be beaten and revered Ahmad ibn Hanbal and bestowed upon him, but (Ahmad) refrained from that. He was then ordered to be taken to his house and was taken.’~ Taken from Usool as-Sunnah by Imam Ahmad bin Hanbal
Al-Tabari states that al-Mu'tasim fell ill on October 21, 841. His regular doctor had died the previous year and the new physician did not follow the normal treatment, and this was the cause of the caliph's illness. Al-Mu'tasim passed away on January 5, 842 (p. 207). This caliph is described by al-Tabari as having a relatively easy going nature, being kind, agreeable and charitable. He was succeeded by his son, al-Wathiq.
The name al-Mu'tasim is also used for a fictional character in the story The Approach to al-Mu'tasim by Argentine author Jorge Luis Borges, which appears in his anthology Ficciones. The al-Mu'tasim referenced there is probably not the Abbasid Caliph of the name, though Borges does state regarding the original, non-fictional al-Mu'tasim from whom the name is taken: "The name is the same as that of the eighth Abbasside, who was victor in eight battles, engendered eight male and eight female children, left behind eight thousand slaves and reigned during eight years, eight moons, and eight days."