 The terror against the communist Partisans and their supporters was ideologically driven.MacDonald's personal opinion, which he admits "may well be refuted in future years" is that “genocide (of Serbs or Croats) in the occupied and divided Yugoslavia during the Second World War is very difficult to prove.” The Ba Congress held in January 1944 marked a change in the main war objective of Chetniks, instead of their initial aim to restore the pre-war Yugoslavia as a unitary monarchy, they accepted Yugoslavia as a federal state structure with a dominant Serb federal unit.Before being adopted by the Chetnik movement, the word "četnik" was commonly used to describe a member of any Balkan guerrilla force called "cheta" (чета / "četa"), meaining "military company".