Yashvil took part in a number of significant military campaigns, including during the French invasion of Russia, the Russo-Turkish War (1787–1792) and the Kościuszko Uprising.

He had an older brother Vladimir, who would also rise to the rank of a General and become personally involved in the assassination of Emperor Paul I of Russia.

Yashvil graduated from the cadet corps as an artillery officer in 1786 and took part in the Russo-Turkish War (1787–1792), earning the rank of lieutenant after the success at Kinburn and Ochakov.

Following the peace treaty Yashvil deployed to Poland for the Polish campaign of 1794, where he played a decisive role in initial victories that culminated in the unsuccessful Siege of Warsaw.

During a field inspection of the army in Champagne, Russian regent Alexander I awarded general Yashvil with the Order of Saint Vladimir 1st degree, for the brilliant state of the imperial artillery.