During World War II, the present-day border between Slovenia and Croatia in the Obsotelje region was the southern border of the German Reich. The border which ran along the Sotla River was protected by the Germans with a high wire fence and with land mines spread over a zone several kilometres wide. The border was additionally guarded by observation towers. After 1944, large-scale fortification works were begun along the entire border. They built firing trenches, machine-gun nests and bunkers, whose remnants are still clearly visible in the landscape today. The border could be crossed only at the guarded border crossings, which greatly changed the daily lives of the local population, many of whom owned land in both countries. Despite the hindered crossing of the border, lively smuggling activities developed across the Sotla River, while the land mines represented a means of arming the partisans. However, the land mines were also the main cause of numerous casualties among the population, even several years after the war had ended.