The participation of Kuban mounted regiments and plastun battalions in the Russian-Japanese war, their courage, bravery and knowledge of service rules by ordinary, their commanders, medical assistants is shown in the article. It is stressed that some cossacks had to fulfill police functions during the years of the first Russian revolution the catalyst of which became Russian-Japanese war. Regiments were sent under the imperial decree to the most disturbing places where the government expected revolutionary revolts.