Prior to the revolution of 1648, Cossacks living on Ukrainian lands were nominally under the jurisdiction of the Polish Kingdom.

By the second half of the sixteenth century, when they had developed into a well-organized military force, there existed two types of Cossacks: (1) town Cossacks, who lived in or near frontier bor­der towns and who were in the service of the Polish administration; and (2) Zapo- rozhian Cossacks, who lived farther south in the no-man’s-land below the bend of the Dnieper River between the Polish Kingdom and the Crimean Khanate.

Both the town Cossacks and the Zaporozhian Cossacks were charged, or charged themselves, with the defense of the Polish frontier against incursions by the Tatars and Ottoman Turks. Both groups also led offensive campaigns in con­cert or alone against their traditional Tatar and Ottoman enemies in the south. Especially during the early decades of the seventeenth century, they frequently fought with Poland’s armies in its wars against Sweden, the Livonian Knights, and Muscovy. As both groups of Cossacks were drawn more and more into Polish mili­tary ventures, they also were affected by Poland’s attempts to gain greater control over their activity.

Registered and unregistered Cossacks

One result of Polish interference in Cossack life was a greater differentiation between the two Cossack groups. This differentiation was symbolized most graph­ically by the policy of registration, whereby registered Cossacks, most often from the border towns, were made an integral part of the Polish frontier military administration. The unregistered Cossacks, mostly in Zaporozhia, in contrast remained beyond the pale of Polish authority, with the consequence that their territory was viewed with suspicion as a place where runaway serfs and others who posed a potential threat to the Polish-Lithuanian social order found refuge.

The registered Cossacks, who by the first half of the seventeenth century ranged in number from about 6,000 to 8,000, resided in or near the Polish admin­istrative centers in the Kiev, Bratslav, and Chernihiv palatinates.

The unregistered Cossacks consisted of two groups: (1) Cossacks from Zaporo- zhia and even farther north who may have served with the Polish army in its time of need (in 1620 the register reached 20,000), but who were soon after removed from the register; and (2) a steady stream of peasants and others who, discontent with the increasing burdens of serfdom, fled south to lead the Cossack way of life in landlord-less Zaporozhia.

The fortified center of Zaporozhia, the sich, moved several times in the course of the seventeenth century, usually progressively southward onto islands or among tributaries of the Dnieper River. By the second half of the century, the sich had developed a more organized administrative structure. While the Sich Council (sichova rada), made up of all members who had equal votes, remained the high­est source of authority in administrative and military matters, it was often unwieldy and gradually gave way to the decisions set by the Council of Elders (rada starshyri). The latter council was made up of an elected judge, a chancellor (pysar), an aide-de-camp (osaul), lieutenants of the varying military units (kunnni otamany), and the head or chief of the sich, the koshovyi otaman. Whereas at various times the sich elected its own hetmans (Sahaidachnyi, Khmel’nyts’kyi), by the sec­ond half of the seventeenth century the office of koshovyi otaman had replaced that of the hetman as the highest office in Zaporozhia.

Apart from the sich, the steppe region immediately on both sides of the Dnieper River was inhabited by married Cossacks and free homesteaders, that is, former serfs and others who had come to Zaporozhia to lead the Cossack way of life. As well as engaging in fishing, hunting, cattle raising, and, later, farming, the married Cossacks and free homesteaders joined the Cossacks from the sich in raids against the Tatars and Turks, served in the foreign ventures of the Polish kings, and took part in attacks against Polish military forces and local administra­tors during times of Polish-Cossack friction. Satisfied with their own situation beyond the reach of Polish royal and local noble governmental authority, the unregistered Cossacks in the sich and in the surrounding Zaporozhian country­side were often suspicious of the town Cossacks and, later, starshyna farther north. Consequently, during the frequent revolts against Polish rule, the Zaporozhian Cossacks were often pitted against registered Cossacks in Polish service.

Internal administration

As a registered Cossack and aspiring member of the gentry, Bohdan Kmel'nyts'kyi initially hoped to obtain personal justice and to uphold and improve the status of