The paper aims to highlight the history of fortifications built by the expedition of Alexander Cherkassky on Mangghyshlaq peninsula in the wide context of international relations between Russia, Khanate of Khiva and Turkmen tribes in Peter's Age. Historiographical overview indicated lack of new approaches to the problem and absence of any serious attempts to find the fortresses. Instead of the exact information on the number of the objects (two) there was a misapprehension that there were three posts. Not only published sources were examined by the staff, but also some archival documents were explored. During the source studies an unkown map made by a participant of the mission of 1716-1717 was discovered. Authors used the findings of the current field study on Manghyshlaq peninsula. The analysis of memoirs of the topographers who visited this area since the middle of XVIIIth century highlighted the process of fortresses remains extinction and changing of the perception of the events of 1716-1717 among Russians and nomads. The history of monument to the participants of Alexander Cherkassky expedition was also traced. As a result they precised supposed location of the St. Peter fortress and unveiled one of the main causes of Cherkassky's failure which was his aspiring to rely predominantly on the Khiva nobles without getting sufficient Turkmen support.