Building on its experience in clandestine operation across the country, the KPJ proceeded to organise the Yugoslav Partisans, as resistance fighters led by Tito. The KPJ assessed that the German invasion of the Soviet Union had created favourable conditions for an uprising and its politburo founded the Supreme Headquarters of the National Liberation Army of Yugoslavia ("Narodonooslobodilačka vojska Jugoslavije") with Tito as commander in chief on 27 June 1941.