Today, Russian Cossacks are led by Atamans, and Ukrainian Cossacks by Hetmans.

Cossack on duty (portrayal of 16th–17th century), painting by Józef Brandt

After the split of Ukraine along the Dnieper River by the Polish-Russian Treaty of Andrusovo in 1667, Ukrainian Cossacks were known as Left-bank and Right-bank Cossacks.

The ataman had executive powers, and at time of war, he was the supreme commander in the field. Legislative power was given to the Band Assembly (Rada). The senior officers were called starshyna. In the absence of written laws, the Cossacks were governed by the “Cossack Traditions” – the common, unwritten law.

Cossack society and government were heavily militarized. The nation was called a host (vois’ko, or viys’ko, translated as ‘army’). The people and territories were subdivided into regimental and company districts, and village posts (polky, sotni, and stanytsi). A unit of a Cossack troop could be called a kuren.^[104]