This book examines events associated with two opposing trends in international politics in the 1920s and 1930s. The essence of the first is that after the Great War of 1914-1918. The governments of the Entente countries seriously dreamed of a Great Peace. Having emerged victorious from the monstrous massacre, having disarmed their former opponents, they believed that in the future they would be able to resolve disputes among themselves through negotiations. Therefore, they created the League of Nations and imposed serious quantitative and qualitative restrictions on their ground, air and naval forces. The essence of the second trend was that, contrary to the good intentions of the leadership of the great powers, over twenty years there were more than thirty military conflicts and local wars. The building of the international world order was persistently set on fire from different sides. In the end, the fire of a new worldwide massacre broke out, even more large-scale and cruel than the first. Both of these trends are examined in detail in this book based on facts related to the development and use of the navies of great and minor sea powers.