In addition, the Bulgarian government tried to alter the ethnic composition of the region, by expropriating land and houses from Greeks in favour of Bulgarian settlers. The same year, the German High Command approved the foundation of a Bulgarian military club in Thessaloníki. The Bulgarians organized supplying of food and provisions for the Slavic population in Central and Western Macedonia, aiming to gain the local population that was in the German and Italian occupied zones. The Bulgarian clubs soon started to gain support among parts of the population. Many Communist political prisoners were released with the intercession of Bulgarian Club in Thessaloniki, which had made representations to the German occupation authorities. They all declared Bulgarian ethnicity. In 1942, the Bulgarian club asked assistance from the High command in organizing armed units among the Slavic-speaking population in northern Greece. For this purpose, the Bulgarian army, under the approval of the German forces in the Balkans sent a handful of officers from the Bulgarian Army, to the zones occupied by the Italian and German troops to be attached to the German occupying forces as "liaison officers". All the Bulgarian officers brought into service were locally born Macedonians who had immigrated to Bulgaria with their families during the 1920s and 1930s as part of the Greek-Bulgarian Treaty of Neuilly which saw 90,000 Bulgarians migrating to Bulgaria from Greece.