In autumn 1621, at a fortified camp near Khotyn (Chocim), in the Principality of Moldavia, allied Polish, Lithuanian and Cossack armies faced a large Ottoman army led by Sultan Osman II. It was the concluding act of a war that had started with the defeat of a Polish army at Cecora one year earlier. As such it was actually part of the longer conflict, waged over the Commonwealth's and the Ottoman's influence over Moldavia. Throughout the whole of September and the first half of October 1621, the allied army managed to defend their camps against Turks, with both sides taking heavy losses from the hardship of the siege operations and worsening weather conditions. The conflict ended with the Treaty of Khotyn (9 October 1621) which did not particularly favor either of the sides. All the same, stopping the Ottoman was seen as a huge success for the Commonwealth, while attitudes on the Ottoman sides were far from victorious. The aftershock of the war led to the rebellion of janissaries in 1622, resulting in the overthrow and murder of Sultan Osman II.The book focuses on the Khotyn campaign of 1621, describing the day-by-day actions of the combatant armies - assaults, sallies and raids - during the whole of the siege. Additional theaters of war, such as Cossack operations from the summer of 1621 and Tatars raids against the Polish interior, are described as well. The reader will also find here details of the organization and strength of the fighting armies, information about the battle dispositions of the troops at Khotyn and commanders leading the troops. Actions leading to the outbreak of the open conflict between the Commonwealth and the Ottoman Empire are explained in a separate chapter, providing a good historical background of the war. Another chapter covers the outcome of the war and the ways that influenced the internal and external situation of both the Commonwealth and the Ottoman Empire.As with his previous works, the author has utilized a large number of primary sources: from the diaries of soldiers taking part in the campaign, through chronicles, official letters and documents from the period to army musters. Among the documents used are not only those written by Poles and Lithuanians, but also documents from Cossacks, Germans and Ottomans. Modern works, especially from Polish and Ukrainian historians, have also been used, in order to provide the most up-to-date and in-depth research. As this topic has previously not had much coverage in English, this book will be a valuable addition to the library of anyone interested in the history of the Polish-Lithuanian Commonwealth, in Zaporozhian Cossacks and in the Ottoman Empire in the early seventeenth century.