Due to its specific geographical position, the territory of Southern Croatia was under direct influence of all the happenings caused by Serbian rebellion in Herzegovina, and vice versa. There was always a strong mutual connection between these two territories in their history, and so it was during the war conflicts in the years of 1991 and 1992. The two major issues in my work here are following: 1) How much was the region of Herzegovina involved in Serbian efforts and aspirations to conquer the Southern Croatian territory, with the City of Dubrovnik as their utmost and most desired point? 2) How important and crucial was the coordination between Croatian people from both sides of the frontier – Croatian and Herzegovinian, and in what ways was it an important background for undertaking all the neccessary operations in order to preserve the unity of Croatian territory and liberate it from Serbian occupation? This obvious Serbian militaristic intention to cut off the South of Croatia from the rest of the country, made Croatians, both from Croatia and Herzegovina, organise their first offensive lines. The valley of the Neretva River, as well as Croatian people living there, were heavily attacked by the agressor who looked at them as an unseparable unit regardless whether it was Croatian or Herzegovinian territory. Regarding all these and taking a specific geographical position of the utmost South of Croatiainto account, Croatian defense was consequently forced to undertake some actions. This specific demographic and ethnic picture of the area, where Croats made the majority of population on both sides of the frontier, turned out to be very convenient for the Croatian side. Despite this fact that made it easier to organise defensive lines, there was still a huge discrepancy concerning the number of people and their arming during 1991, which made the defensive lines hard to organise. At the beggining of 1992, the war officialy spread out to the territory of Bosnia and Herzegovina, which made Herzegovina operationally even more connected to Southern Croatia. The unity of the territory and people living there resulted in forming United Croatian Defence Forces in the Southern battlefields with Croatian Army on both sides of the frontier. This was a turning point in the Southern battlefield which, in the end, created favourable conditions for further winning operations to make the Croatian territory free and liberated from the agressor.