Prince of Smolensk
In 1125 Rostislav's father, Saint Mstislav the Great, granted him Smolensk as his inheritance. He governed the principality for more than four decades, expanding it with new cities and villages and adorning it with churches and monasteries. Among the towns associated with his rule are Rostislavl, Mstislavl, Krichev, Propoisk, and Vasiliev. Through this work he became the founder of the Smolensk princely dynasty.
In 1136 Rostislav established an independent diocese of Smolensk, with Bishop Manuel as its first leader, issuing an edict that guaranteed ecclesiastical support; in 1150 he ceded Cathedral Hill to the diocese. He rebuilt the Dormition cathedral originally constructed by his grandfather Vladimir Monomakh, which was consecrated on 15 August 1150. His other construction projects included the Smolensk Kremlin and the Savior cathedral at the Smyadynsk monastery of Saints Boris and Gleb.
Grand Prince of Kiev
Rostislav reclaimed Kiev on 12 April 1159 and ruled as Grand Prince, with interruptions, until his death. Across his career he held Kiev in three periods: briefly in December 1154, from April 1159 to February 1161, and from March 1161 to March 1167. He also served briefly as Prince of Novgorod in 1154. Contemporaries valued his wisdom regarding the civil realm and his strict sense of justice.
In ecclesiastical matters Rostislav initially opposed the autocephaly of the Russian Church, fearing it would fragment the nation, but he later supported Metropolitan Clement Smolyatich, influenced by the Kiev Caves monastery and its Archimandrite Polycarp. He maintained a humble obedience to the ecclesiastical authority of Constantinople.
Piety and Final Days
Rostislav kept the pious custom of inviting the igumen and twelve monks to his own table on the Saturdays and Sundays of Great Lent, serving them himself. He expressed a desire to become a monk at the Caves monastery.
Returning from a campaign to Novgorod in the spring of 1167, Rostislav fell ill. He asked that, if he died on the way, he be buried at his father's monastery, and that, if he recovered, he be received into monastic tonsure. He died on 14 March 1167, and in accordance with his last wishes his body was brought to the Theodosiev monastery in Kiev.