Pardoned a year later, Grigol entered the Russian military service and took part in the concluding phases of the Napoleonic Wars, particularly, the 1813 Polish campaign, of which he left an account. Grigol continued his military service, rising to the rank of podpolkovnik (lieutenant colonel) of the Astrakhan Cossack Regiment. After retirement from the army, he lived in St. Petersburg, focusing on compiling an anthology of Georgian poetry. He died there, at the age of 41, and was buried at the Alexander Nevsky Lavra. Niko Javakhishvili, a historian at Tbilisi State University, suggested in 2008 to include Grigol in the list of the kings of Georgia as Gregory I.