The evolution of peace operations can be divided into three main phases as the period before the League of Nations (antecedents), the League of Nations phase (novice attempts), and the current period beginning after the foundation of the United Nations (maturity). The first phase could begin with the Crusades and end before the establishment of the League of Nations. The following phase covers the period of League of Nations. The third phase starts with the founding of United Nations, and still continues.