The monograph for the first time covered the issues of mobilization in the Belarusian provinces to the Russian army at the beginning of the First World War, the formation of new regiments and squads of the state militia, shows their advancement to places of concentration and deployment for the outbreak of hostilities. The issues of evacuation of the population, institutions and enterprises, the problem of refugee of civilians and its solution on Belarusian lands were investigated. The fighting on the territory of Belarus, the decline in morale in the troops of the Western Front are highlighted, the causes and consequences of this phenomenon are named. It is said that the German troops violated the peace treaty and seized a huge territory, the organization of rebuffing the enemy by the Soviet government is shown.