Following the end of the Second World War and the success of the Yugoslav Partisans in their resistance to the Axis powers, Yugoslavia became a socialist state.
[1] The invasion of Czechoslovakia showed that the standing conventional forces of a small country could not repulse a surprise attack by a qualitatively and quantitatively superior aggressor.
[2] Being strategically positioned between the two major blocs, the NATO and the Warsaw Pact, Yugoslavia had to prepare its own military doctrine for a potential Third World War mass invasion scenario.
It was inspired by the Yugoslav Partisan resistance movement against the Axis powers in the Second World War,[3] and was designed to allow Yugoslavia to maintain or eventually reestablish its independent and non-aligned status should an invasion occur.
[2] The TO would supplement the regular JNA, giving it greater defensive depth and an armed local population ready to support combat actions.
[2] Under the constitution and laws of SFR Yugoslavia as the second part of armed forces, the Territorial Defense Forces were formed in 1969 as an integral part of the Yugoslav Total National Defense doctrine with the task of defending Yugoslav territory and supporting and working with JNA as one means of organized armed resistance through total war doctrine against aggressors.
The TO concept focused on small, lightly armed infantry units fighting defensive actions on a familiar local terrain.
[2] More than 2,000 communes, factories, and other enterprises organized such units, which would fight in their home areas, maintaining local defense production essential to the overall war effort.
Between 1 and 3 million Yugoslavs between the ages of 15 and 65 could fight under TO command as regular or guerrilla forces in wartime with numbers varying during different time-frames of Yugoslavia's existence.
Such concerns became reality during the breakup of Yugoslavia and the Yugoslav Wars when the TO forces in many of the constituent republics switched their allegiance and turned into separatist paramilitaries.