The article is a synthesis of selected problems researched by a team led by Prof. Col. Waldemar Kaczmarek within the research project entitled "Land Forces in Crisis Management System". The author does not solve the whole problem of using Land Forces, but only highlights the problem pointing to the widespread scale of their tasks. In the modern world, apart from threats to the sovereignty of the state, there appear other threats resulting from social, economic, political and geographical conditions. The mentioned above conditions show the reasons of crisis situations and crises of the following character : political and military, where political contradictions cause tense situations leading to a military crisis in international or national relations ; physical and geographical, in which morphological conditions of the universe or irresponsible human behaviour lead to threats to emerge ; social, which result from not fulfilling basic human needs. Land Forces’ selected sub-units may participate in liquidating or neutralizing negative effects of crisis situations or political and military, physical and geographical, and social crises. If they were to operate effectively, one should identify reasons why crises appear and legal procedures of the Armed Forces engagement, which are the basis to determine their tasks.