SAT was founded in 1921 by
Eugène Lanti (pseudonym of Eugène Adam) and others as an organisation of the
workers' Esperanto movement. It was the largest and most active between the two World Wars. At its high point in 1929-1930 it had 6524 members in 1674 communities in 42 countries. It suffered heavy attrition soon after, however, when "
cosmopolitan" activities, a category into which Esperanto fell, began to be persecuted in the Soviet Union after the onset of Stalinism, and after the ban on the workers' Esperanto movement in Germany that took effect immediately after the
Nazi takeover in 1933. The Soviet Union and Germany had been the countries in which SAT had the greatest number of members. Ideologically motivated internal schisms, involving at various times anarchists, communists and social democrats, also took a toll. ==Aims==