Lukačević and his Chetniks were drawn into closer collaboration with the Axis during the second phase of Case White, which took place in the Neretva and Rama river valleys in late February 1943 and was one of the largest anti-Partisan offensives of the war.
In February 1943, during the second phase of Case White, Lukačević and his Chetniks jointly held the town of Konjic on the Neretva river alongside Italian troops.