The book is dedicated to the attempt of the Ukrainian People's Republic in April 1918 to include the Crimean peninsula, having previously freed it from the Bolsheviks who had previously usurped power there. The book tells about the interpretation of the "Crimean problem" on the world stage in March 1917 - April 1918, about the forces and plans of the parties, about the course of hostilities on the peninsula and about the missed unique opportunity to annex Crimea to Ukraine a hundred years ago.