Editing Abbas Mirza (section)

=== War with the Ottoman Empire ===
{{Main|Ottoman–Persian War (1821–1823)}}
[[Image:An official copy of the treaty of Erzurum, Persia, Qajar, 19th Century.jpg|thumb|An official copy of the [[Treaty of Erzurum]]. [[Persian language|Persian]] manuscript, created in Qajar Iran, 19th century]]
The conflict between Iranian and Ottoman border authorities was a major factor in the decline of Iranian-Ottoman relations between 1818 and 1820. Political issues in the Kurdish principality [[Baban]] renewed the animosity between Dowlatshah and the Ottoman governors of [[Baghdad]], [[Sulaymaniyah]], and [[Shahrizur]] in the central and southern sections of the Iranian-Ottoman frontier. The relation between Abbas Mirza and the Ottoman ''[[serasker]]'' of [[Erzurum]] was also made worse due to a dispute over the control of the nomadic tribes that inhabited the northern frontier.{{sfn|Shahvar|2020a|pp=562–563}} Abbas Mirza first opted for a diplomatic solution to the problems, and the British supported him in this decision. They made every effort to keep the Iranians and Ottomans from fighting each other, as it could weaken both sides and thus make it easier for the Russians to advance further south to India.{{sfn|Shahvar|2020a|p=563}}{{sfn|Shahvar|2020b|p=125}}

The Iranians and Ottomans were unable to find a solution, and following the eruption of the [[Greek war of independence]] against the Ottomans in 1821, Abbas Mirza offered Russia that they make a joint assault on the Ottoman Empire. He may have believed that a joint assault on the Ottoman Empire would deter Russia from considering additional attacks against Iran or at the very least further weaken the Russian military. His offer was declined by Russia, who nevertheless encouraged Iran to attack the Ottomans, even offering them financial help. The Russians may have hoped that a conflict between Iran and the Ottoman Empire would weaken them both, thus making it easier for them to advance further south.{{sfn|Shahvar|2020a|p=563}}

In the same year, Dowlatshah invaded [[Ottoman Iraq]], reaching as far as the walls of Baghdad.{{sfn|Busse|1982|pp=79–84}} Dowlatshah was forced to leave due to a [[cholera epidemic]], which he later contracted himself in November. While a second Iranian force conquered [[Bitlis]] and pushed towards [[Diyarbakr]], Abbas Mirza distinguished himself by capturing [[Doğubayazıt|Bayazit]] and Toprak Qala and marching on to Erzerum. In May 1822 at Khoy, Abbas Mirza successfully defeated the Ottoman counterattack, but by this point, cholera had also spread throughout his force, leading him to sue for peace.{{sfn|Hambly|1991|p=163}} In contrast to earlier conflicts, no [[Anti-Shi'ism|anti-Shia]] [[fatwa]]s were ever declared by the Ottoman clergy to support the war. During peace negotiations, the Ottoman [[Shaykh al-Islam]] sent a letter to Abbas Mirza, in which he praised their friendship and referred Iran and the Ottoman Empire as "two great countries that are as one body."{{sfn|Tucker|2006|pp=561–564}}