 Complete the following phrase:  In 1838, Ivan Krasnov was elected the director of the board of the Don Cossack Voisko and assistant to the Ataman for civil affairs. In 18411842 he served as Cossack field chieftain of Don Cossack Voisko regiments in the Caucasus and wrote the book Notes on the War in Caucasus Записки о кавказской войне. In 18431848 he commanded the Life Guards of the Cossacks regiment. During Crimean War Krasnov served in the rank of field chieftain ataman of Don Cossack Voisko regiments within the Crimean Army, and organized the defense of the city of Taganrog during the 