The Russo-Persian War of 1826-1828 was the last major military conflict between the Russian Empire

Russian Empire

The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...

 and the Persian Empire

Qajar dynasty

The Qajar dynasty was an Iranian royal family of Turkic descent who ruled Persia from 1785 to 1925....

.

After the Treaty of Gulistan concluded the previous Russo-Persian War in 1813, peace reigned in the Caucasus

Caucasus

The Caucasus, also Caucas or Caucasia , is a geopolitical region at the border of Europe and Asia, and situated between the Black and the Caspian sea...

 for thirteen years. However, Fath 'Ali Shah, constantly in need of foreign subsidies, relied on the advice of British

United Kingdom of Great Britain and Ireland

The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom during the period when what is now the Republic of Ireland formed a part of it....

 agents, who pressed him to reconquer the territories lost to Russia and pledged their support to military action.