There were different yesaul posts and ranks in Cossack Hosts in Imperial Russia: In Ukraine of the 17th and 18th centuries, an osaul was a military and administrative official performing the duties of aide-de-camp.
Beside them there were osauls under special assignments, one of them serving for General Obozny (quartermaster) who performed duties of a chief executive and was the second in importance after the Hetman.
Other duties consisted of being a hetman's envoy, supervised matters of internal security, conducted annual regimental musters and inspections.
Sotenny Osavul (Ukrainian: Сотенний осавул) is an assistant sotnik in Military Affairs.
In the ukrainian folk song "Zadumaly Bazylevtsi" (Задумали Базилевці) about the anti-serfdom uprising in Turbaii (1789—1793), the wife of the Bazylevskyj family sends Yesauls to take care of the serfs, but they are met with unexpected resistance.