The Supreme Headquarters, which was in Foča until 10 May 1942, managed, with the help of the 1st and 2nd Proletarian Brigades, to withdraw part of the partisan forces from Montenegro and Herzegovina and form new units from them: 3rd Proletarian Sandžak Brigade, 4th and 5th Proletarian Montenegrin Brigade and the Herzegovina Detachment. June 19, 1942. Decision of Partisan Supreme HQ to move west proved to be very prudent for a number of reasons, the most important of which was that the Italians, on the basis of the Zagreb agreement concluded on June 19, withdrew a large part of their troops from zones II and III. Ustashe regime had neither the time nor the strength to adequately protect these areas. Group of brigades, which consisted of: the 1st and 2nd Proletarian, 3rd Sandžak and 4 Montenegrin Brigades, together the Supreme Headquarters, moved from the Zelengora region on 24 June 1942 to western Bosnia in the general direction Kalinovik-Prozor-Kupres. 5th Proletarian Montenegrin Brigade and the Herzegovinian Detachment with a partisan hospital were left on the border of Herzegovina, Montenegro and Bosnia, in order to penetrate Montenegro and Herzegovina in a more favorable situation. After managing to break up the Ustasha forces around the
Treskavica mountain, on 3 July 1942, partisan brigades carried out a surprise attack on the Sarajevo-
Konjic railway between
Hadžići and Konjic. During the night, the brigades defeated the enemy crews at the stations, destroyed important station facilities, destroyed the railway in several places, as well as all important bridges. Dozens of wagons and several locomotives were destroyed.
Attack on Konjic After a series of diversions on the railway, 1st Proletarian Brigade broke up the enemy garrison in Konjic on the night between July 7 and 8, defending a battalion of
Croatian Home Guard and two
Ustasha companies, liberated the city and destroyed the railway station and furnace with about 25 locomotives. This was a major blow to the occupying forces and the NDH, because ties with Herzegovina were severed for more than two months and the transport of
bauxite from the Mostar region was prevented. From the railway, partisan brigades Group continued its operations in two directions: the right column, composed of 2nd Proletarian and 4th Montenegrin Brigade, attacked the enemy garrisons in the upper course of the Vrbas via
Bitovanje and
Vranica; the left column, made up of 1st Proletarian and 3rd Sandžak Brigades, headed in the direction of Prozor-Livno. After the capture of
Gornji Vakuf, the right column fought fierce battles around Bugojno and
Donji Vakuf, while the left column liberated Prozor,
Šujica and
Duvno, and in cooperation with the Dalmatian and Krajina partisans liberated Livno on August 5.
Attack on Livno The liberation of Livno was a great success of the NOVJ. 2nd Battalion of the 1st Proletarian Brigade invaded the city through clearings, high wire barriers and between masonry-concrete bunkers, destroyed the enemy forces it encountered, severed ties and disrupted the enemy's command, and cooperated with other battalions attacking the city. The Ustasha garrison had losses of about 200 dead (including those executed), with its own losses of 5 dead and 20 wounded. Partisans seized all weapons and ammunition, including 6 tons of explosives. About 300 captured members of Home Guard were disarmed and released, and 12 Germans were captured, who were employees of
Organization Todt, that was engaged in the economic exploitation of the occupied areas. These Germans would be exchanged in September for captured partisans and arrested activists. This would the first exchange of prisoners between Partisan forces on the one hand, and the German authorities on the other. At the beginning of August, 5th Proletarian Montenegrin Brigade and the Herzegovinian Detachment arrived in the liberated Prozor, and after fierce fighting with the Axis and Chetnik forces in the wider region of Zelengora, they were forced to move in this direction.
Attack on Kupres Particularly difficult battles were fought group of partisan brigades, composed of 2nd Proleterian and 4th Montenegrin Brigades, parts of 3rd Sandžak and 10th Herzegovinian Brigades (formed on August 10 by the Herzegovinian Detachment and the Konjic Partisan Battalion), together with 1st Krajina Brigade and 3rd Krajina Detachment for Kupres from 11 to 14 August. == Aftermath ==