Azerbaijan doesn’t hide its territorial ambitions towards the border regions of Armenia. This work shows that Baku's aspirations are not new, they have at least 100 years of history. In 1919, the Tatar population of the Sotk region, at the instigation of Azerbaijan, rebelled against the Armenian government and announced its that it is joining Azerbaijan. And only due to "Zod" operation this important region remains part of Armenia. Operation Zod is almost unknown to the general public, while it is one of the brightest pages in the history of the last century of Armenia. For the first time and on the basis of new factual data, the authors of the book present the causes, chronology and consequences of the Armenian-Tatar clashes in the Lake Sevan region.