 Complete the following phrase:  The Chetnik Command  was a military operation plan of the Yugoslav government in an expected invasion of Yugoslavia. It was part of the military plans to lead guerrilla warfare, earlier developed. It was established in April 1940, including the organization of six complete and one incomplete battalion recruited from the regular Royal Yugoslav Army on voluntary basis. The six battalions known as assault battalions, , or Chetnik battalions,  were added to each Field Army of which there were seven, placed in Novi Sad, Sarajevo, Skopje, Karlovac, Niš and Mostar. Its headquarters was transferred from Novi Sad to Kraljevo in south-central Serbia on 1 April. Between 10 July 1940 and 1 April 1941 the official name was the Assault Command . Although a traditional notion, the Yugoslav military did not use the Chetnik idea in its military planning until 1940. It had little support in the highest ranks whose views were formed in World War I. It had the rank of Division, and was directly subordinated to the Ministry of the Army and Navy. The first commander was division general  Mihailo Mihailović. It was activated on 1 April 1941 and saw action in the 