Baltic coast 4–10 September Northern Front Southern Front Sarny Fortified Area (known in Polish in several names: Sarneński Rejon Umocniony, Sarneński Odcinek Umocniony, Bastion Polesie) was a line of bunkers and trenches along both sides of the Sluch River, in the area of the town of Sarny, northern Volhynia, in Ukraine.
As the Polish military authorities regarded the Soviets as the main threat (Plan East), construction of fortifications began in 1936.
Every bunker had up to 30 soldiers of the Border Defence Corps (KOP), who were equipped with 75 mm cannons and machine guns.
The soldiers who remained in the Sarny Fortified Area were ordered in mid-September 1939 to abandon the bunkers and to move with their equipment towards the Romanian Bridgehead.
Several bunkers were blown up by the Red Army engineers with their crews, unknown number of soldiers were murdered, including seven officers, who were shot near the Orthodox church in the village of Tynne.