When World War I broke out in 1914, Tucović stood out especially in the Battle of Cer and the Battle of Kolubara. After the Great Retreat, in 1916, new political games began in which the "blacks", and above all Apis, were blamed for all the misfortune. The reason for the confrontation with the members of the "Black Hand" was the failed assassination of Regent Alexander on 11 September 1916 when someone shot at his car near Thessaloniki. Immediately afterwards, Dragutin Dimitrijević Apis and other members of the "Unification or Death" organization were arrested, including cavalry lieutenant colonel Vladimir Tucović.