After the fall of Yugoslavia in April 1941, Mihailović organized the Chetniks at Ravna Gora and engaged in guerrilla warfare alongside Josip Broz Tito's Partisans against occupying German forces.

Many Chetnik groups collaborated or established modus vivendi with the Axis powers, which along with British frustration over Mihailović's inaction led to the Allies shifting their support to Tito in 1944.

Following the war, he became a member of the Royal Guard of the Kingdom of Serbs, Croats and Slovenes but had to leave his position in 1920 after taking part in a public argument between communist and nationalist sympathizers.

Mihailović then came in contact with members of Zveno and considered taking part in a plot which aimed to provoke Boris III's abdication and the creation of an alliance between Yugoslavia and Bulgaria, but, being untrained as a spy, he was soon identified by Bulgarian authorities and was asked to leave the country.

[14] Following the invasion and occupation of Yugoslavia by Germany, Italy, Hungary, a small group of officers and soldiers led by Mihailović escaped in the hope of finding VKJ units still fighting in the mountains.

In August, he set up a civilian advisory body, the Central National Committee, composed of Serb political leaders including some with strong nationalist views such as Dragiša Vasić and Stevan Moljević.

Mihailović sent him back to Montenegro with written authorization to organize units there, with the oral approval of officers such as Đorđije Lašić, Pavle Đurišić, Dimitrije Ljotić and Kosta Mušicki.

[22] Mihailović's Chetniks had had defensive encounters with the Germans, but reprisals and the tales of the massacres in the NDH made them reluctant to engage directly in armed struggle, except against the Ustaše in Serbian border areas.

[30][31] The prospect of reprisals also fed Chetnik concerns regarding a possible takeover of Yugoslavia by the Partisans after the war, and they did not wish to engage in actions that might ultimately result in a post-war Serb minority.

[30] For his part, Tito's goal was to prevent an assault from the rear by the Chetniks, as he was convinced that Mihailović was playing a "double game", maintaining contacts with German forces via the Nedić government.

Eventually, on 6 July 1942, the station Radio Free Yugoslavia, located in the Comintern building in Moscow, broadcast a resolution from Yugoslav "patriots" in Montenegro and Bosnia labelling Mihailović a collaborator.

While Mihailović approved the destruction of communist forces, he aimed to exploit the connections of Chetniks commanders with the Italians to get food, arms and ammunition in the expectation of an Allied landing in the Balkans.

The congress, which historian Stevan K. Pavlowitch writes expressed "extremism and intolerance", nationalist claims were made on parts of Albania, Bulgaria, Romania and Italy, while its resolutions posited the restoration of a monarchy with a period of transitional Chetnik dictatorship.

[87] In the same month, Mihailović informed his subordinates that: "The units of the Partisans are filled with thugs of the most varied kinds, such as Ustašas – the worst butchers of the Serb people – Jews, Croats, Dalmatians, Bulgarians, Turks, Magyars, and all the other nations of the world.

He led the "nationalist" resistance against Partisans and Ustaše and acknowledged Mihailović as the formal leader, but acted on his own, with his troops being used by the Italians as the local Anti-Communist Volunteer Militia (MVAC).

[93] Adolf Hitler wrote to Benito Mussolini on 16 February 1943, demanding that in addition to the partisans be pursued the chetniks who possessed "a special danger in the long-term plans that Mihailovic's supporters were building."

[110] In 1943, Đurišić followed Chetnik Supreme Command orders to carry out "cleansing actions" against Muslims and reported the thousands of old men, women and children he massacred to Mihailović.

[114] He was later convicted of crimes that included having "incited national and religious hatred and discord among the peoples of Yugoslavia, as a consequence of which his Chetnik bands carried out mass massacres of the Croat and Muslim as well as of the Serb population that did not accept the occupation.

"[117] On 15 November 1942, Captain Hudson cabled to Cairo that the situation was problematic, that opportunities for large-scale sabotage were not exploited because of Mihailović's desire to avoid reprisals and that, while waiting for an Allied landing and victory, the Chetnik leader might come to "any sound understanding with either Italians or Germans which he believed might serve his purposes without compromising him", in order to defeat the communists.

While Ribbentrop and Hitler finally overruled the orders of their subordinates and forbade any such contacts, the Partisans benefited from this brief truce, during which Italian support for the Chetniks was suspended, and which allowed Tito's forces to deal a severe blow to Mihailović's troops.

Đurišić, having escaped from a German camp in Galicia, found his way to Yugoslavia, was captured again, and was then asked by collaborationist prime minister Milan Nedić to form a Montenegrin Volunteer Corps against the Partisans.

[144] In the chaotic situation created by the Italian surrender, several Chetnik leaders overtly collaborated with the Germans against the reinforced Partisans; approached by an Abwehr agent, Jevđević offered the services of about 5,000 men.

[145] In October 1943, Mihailović, at the Allies' request, agreed to undertake two sabotage operations, which had the effect of making him even more of a wanted man and forced him, according to British reports, to change his headquarters frequently.

On 12 September, King Peter broadcast a message from London, announcing the gist of 29 August's decree and calling upon all Serbs, Croats and Slovenes to "join the National Liberation Army under the leadership of Marshal Tito".

It appears that Nedić offered to obtain arms from the Germans, and to place his Serbian State Guard under Mihailović's command, possibly as part of an attempt to switch sides as Germany was losing the war.

Tomasevich suggests one main cause of his defeat was his failure to grow professionally, politically or ideologically as his responsibilities increased, rendering him unable to face both the exceptional circumstances of the war and the complex situation of the Chetniks.

[194] Tomasevich also criticizes Mihailović's loss of the Allied support through Chetnik collaboration with the Axis, as well as his doctrine of "passive resistance" which was perceived as idleness, stating "of generalship in the general there was precious little.

"[201] In the United States, due to the efforts of Major Richard L. Felman and his friends, President Truman, on the recommendation of Eisenhower, posthumously awarded Mihailović the Legion of Merit for the rescue of American airmen by the Chetniks.

In the 1980s, political and economic problems within Yugoslavia undermined faith in the communist regime, and historians in Serbia began a re-evaluation of Serbian historiography and proposed the rehabilitation of Mihailović and the Chetniks.

[209] Vojislav Šešelj's Serbian Radical Party formed the White Eagles, a paramilitary group considered responsible for war crimes and ethnic cleansing, which identified with the Chetniks.