| Mohammad Shah Qajar | |
|---|---|
| Shahanshah Khaqan son of Khaqan Ghazi | |
 Mohammad Shah in 1838 | |
| Shah of Iran | |
| Reign | 23 October 1834 – 5 September 1848 |
| Coronation | 14 January 1835 |
| Predecessor | Fath-Ali Shah Qajar |
| Successor | Naser al-Din Shah |
| Born | Mohammad Mirza محمد میرزا 5 January 1808 Tabriz, Qajar Iran |
| Died | 5 September 1848 (aged 40) Tehran, Qajar Iran |
| Burial | |
| Wives | Seven, among them, Malek Jahan Khanom |
| Issue Detail | See Below |
| Dynasty | Qajar |
| Father | Abbas Mirza |
| Mother | Galin Khanum |
| Religion | Shia Islam |
| Tughra |  |
Mohammad Shah (Persian: محمدشاه قاجار; born Mohammad Mirza; 5 January 1808 – 5 September 1848) was the third Qajar shah of Iran from 1834 to 1848, inheriting the throne from his grandfather, Fath-Ali Shah. From a young age, Mohammad Mirza was under the tutelage of Haji Mirza Aqasi, a local dervish from Tabriz whose teachings influenced the young prince to become a Sufi-king later in his life. After his father Abbas Mirza died in 1833, Mohammad Mirza became the crown prince of Iran and was assigned with the governorship of Azarbaijan. After the death of Fath-Ali Shah in 1834, some of his sons including Hossein Ali Mirza and Ali Mirza Zel as-Soltan rose up as claimants to the throne. With the support of English and Russian forces, Mohammad Shah suppressed the rebellious princes and asserted his authority.
Mohammad Shah dismissed and executed his tactful premier, Abol-Qasem Qa'em-Maqam, and appointed his favourite, Haji Mirza Aqasi, as the grand vizier. The new shah's main goal was to reestablish the rule of the Iranian government in the rebellious city of Herat. In 1837 he marched to Herat and laid a futile siege on the city, which was eventually withdrawn when the British government threatened to invade Iran. On his return, Mohammad suppressed a revolt in Isfahan led by the major clergy figure Mohammad Bagher Shafti. Through British-Russian mediation, he concluded the Second Treaty of Erzurum with the Ottoman Empire, after initially wanting retaliation for the sack of Khorramshahr by the Ottoman governor of Baghdad.
Due to British pressure, Mohammad Shah reluctantly prohibited the slave trade through the Persian Gulf, but still allowed the possession and trade of slaves in the country. During the rise of the Bábism faith and its prophet Báb, Mohammad refused to persecute them despite the fatwa (decree) imposed by Shiite clerics. Diplomatic relations between France and Iran recommenced during his reign. Mohammad suffered from gout, which overshadowed his reign. In the final years of his life, his physical health deteriorated, leading to his death from a combination of gout and erysipelas on 4 September 1848 at the age of 40 after fourteen years of reign. He was buried at the Fatima Masumeh Shrine in Qom and was succeeded by his son, Naser al-Din Shah.
As a ruler, Mohammad Shah did not receive praise. He was labeled as a figurehead king for Aqasi, whom he was highly dependent on. Mohammad was devoted to both Aqasi and his teachings on Sufism; he became a willing sustainer of Sufis, and sought spiritual guidance in mystical rituals instead of the marji'i taqlīd (Shiite clerics). The ulama grew as his firmest rivals, who challenged his legitimacy and authority throughout his short reign. Mohammad enlarged the Qajar bureaucracy, and filled governmental positions with Aqasi's Sufi friends and companions, thus establishing a corrupt administration that saw its peak during his son's reign. Mohammad Shah was the last Qajar king who attended the battlefield in a foreign war, and was also the last to use the title Ghazi (warrior of Islam) for his activity in the Iran-Russia war and for suppressing the rebellion in Isfahan.