Bohdan Khmelnytsky in the context of "Treaty of Pereyaslav"

Ukrainian nationalism (Ukrainian: Український націоналізм, romanized: Ukrainskyi natsionalizm, pronounced [ʊkrɐˈjinʲsʲkɪj nɐts⁽ʲ⁾ionɐˈl⁽ʲ⁾izm]) is the promotion of the unity of Ukrainians as a people and the promotion of the identity of Ukraine as a nation state. The origins of modern Ukrainian nationalism emerge during the Cossack uprising against the Polish–Lithuanian Commonwealth led by Bohdan Khmelnytsky in the mid-17th century. Ukrainian nationalism draws upon a single national identity of culture, ethnicity, geographic location, language, politics (or the government), religion, traditions and belief in a shared singular history.

The Cossack Hetmanate (Ukrainian: Гетьма́нщина, romanized: Hetmanshchyna; see other names), officially the Zaporozhian Host (Ruthenian: Войско Zапорожскоε; Ukrainian: Військо Запорозьке, romanized: Viisko Zaporozke; Latin: Exercitus Zaporoviensis), was a stratocratic Zaporozhian Cossack state established by Registered Cossacks in Dnieper Ukraine. Its territory was located mostly in region of Central Ukraine, as well as in parts of Belarus and southwestern Russia, and at different points it also incorporated the territories of Zaporozhian Sich to the south. The Hetmanate existed between 1649 and 1764, although its administrative-judicial system persisted until 1781. In different periods it was a vassal of the Polish–Lithuanian Commonwealth, Ottoman Empire and Russian Empire.

The Hetmanate was founded in the eastern territories of the Polish–Lithuanian Commonwealth by the Treaty of Zboriv, signed on August 18, 1649 by Bohdan Khmelnytsky (Hetman of the Zaporizhian Host) and Adam Kysil (representing Crown Forces), as a result of Khmelnytsky Uprising. Establishment of vassal relations with the Tsardom of Russia in the Treaty of Pereiaslav of 1654 is considered a benchmark of the Cossack Hetmanate in Soviet, Ukrainian, and Russian historiography. The second Pereiaslav Council in 1659 restricted the independence of the Hetmanate, and from the Russian side there were attempts to declare agreements reached with Yurii Khmelnytsky in 1659 as nothing more than the "former Bohdan's agreements" of 1654. The 1667 Treaty of Andrusovo, conducted without any representation from the Cossack Hetmanate, established the borders between the Polish and Russian states, dividing the Hetmanate in half along the Dnieper and putting the Zaporozhian Sich under a formal joint Russian-Polish administration.

The Khmelnytsky Uprising, also known as the Cossack–Polish War, Khmelnytsky insurrection, or the National Liberation War, and Cossack Revolution, was a successful Cossack rebellion with elements of religious war that took place between 1648 and 1657 in the eastern territories of the Polish–Lithuanian Commonwealth, resulting in Cossack victory and the creation of the Cossack Hetmanate in present-day Ukraine. Under the command of Cossack Hetman Bohdan Khmelnytsky, the Zaporozhian Cossacks, allied with the local Ruthenian (Ukrainian) peasantry and initially the Crimean Tatars, fought against the Commonwealth's forces. The war was accompanied by mass atrocities committed by Cossacks against prisoners of war and the civilian population, especially Poles, Jews, Roman Catholic and Ruthenian Uniate clergy, as well as savage reprisals by the Polish szlachta and the loyalist Jeremi Wiśniowiecki, the voivode of Ruthenian descent (military governor) of the Ruthenian Voivodeship.

The uprising has a symbolic meaning in the history of Ukraine's relationship with Poland and Russia. It ended the Polish Catholic szlachta's domination over the Ukrainian Orthodox population; at the same time, it led to the eventual incorporation of eastern Ukraine into the Tsardom of Russia initiated by the 1654 Pereiaslav Agreement, whereby the Cossacks would swear allegiance to the tsar while retaining a wide degree of autonomy. The event triggered a period of political turbulence and infighting in the Hetmanate known as the Ruin. The success of the anti-Polish rebellion, along with internal conflicts in Poland and concurrent invasions waged by Russia and Sweden against the Poles, ended the Polish Golden Age and caused a secular decline of Polish power during the period known as "the Deluge".

The Treaty of Zboriv was signed on August 18, 1649, after the Battle of Zboriv when the Crown forces of about 35,000, led by King John II Casimir of Poland, clashed against a combined force of Cossacks and Crimean Tatars, led by Hetman Bohdan Khmelnytsky and Khan İslâm III Giray of Crimea respectively, which numbered about 50,000.

The Treaty of Zboriv consisted of two separate agreements between Ukraine and the Commonwealth and between Crimea and the Commonwealth.

The Batoh (Batih) massacre (Polish: Rzeź polskich jeńców pod Batohem) was a mass execution of Polish captives after the Battle of Batih on 3–4 June 1652 near Ladyzhyn (now in Ukraine). It was carried out by Ukrainian Cossacks under the command of Hetman Bohdan Khmelnytsky.

Initially the captured Polish soldiers belonged to the Cossacks' allies, the Crimean Tatars. After the battle, the Cossacks paid the Tatars for possession of the prisoners, and promptly slaughtered the Polish captives to avenge Khmelnytsky's defeat at Berestechko in June 1651. According to Jasienica, it was the Cossack colonels Ivan Zolotaryenko and Ivan Vysochin who bought them from the Tatars. According to Widacka, Cossack's commander Khmelnytsky himself contributed 50,000 thalers for that purpose. According to Hrushevsky and Pasicznyk, Duda, and Sikora, the decision to execute the prisoners was made by Khmelnytsky himself. Afterward, between 3,000 and 5,000 and 8,000 Polish soldiers were tied up and massacred in two days of methodical beheadings and disembowelments. Zolotaryenko supervised the executions yelling "Revenge for Berestechko!", a reference to an earlier Cossack defeat at the hands of the Poles in the Battle of Berestechko.

The Pereyaslav Articles (Ukrainian: Переяславські статті, romanized: Pereiaslavski statti, Russian: Переяславские статьи, romanized: Pereyaslavskiye stati) were concluded on 27 October 1659 between Yurii Khmelnytsky, the son of Bohdan Khmelnytsky, and the Russian tsar. The treaty was an aftermath of the Treaty of Hadiach on 16 September 1658 between the Cossacks and the Polish–Lithuanian Commonwealth, which granted many privileges to Cossacks and thus threatened Russian influence over them. The articles imposed severe restrictions on Cossack Hetmanate's autonomy.