Fortified Area of Silesia The Fortified Area of Silesia ( ) was a set of Polish fortification s , constructed along the interbellum border of Poland and Germany in the area of then - divided Upper Silesia . It spreads from the village of Przeczyce in the north to the town of Wyry in the south , along the line of sixty kilometers . Headquarters of the area was placed in Chorzów and its commandant was General Jan Jagmin - Sadowski . History . As a result of the Plebiscite in Silesia and the Silesian Uprisings , the highly industrialized area of Upper Silesia , which had belonged to the German Empire , was divided between Poland and Germany , leaving Beuthen , Hindenburg and Gleiwitz in Germany and granting both Katowice and Chorzów to Poland . In the 1920s the Poles did not consider their western neighbor as the main threat , concentrating its defence abilities in the East , along the border with the Soviet Union . However , beginning in the early 1930s , after Adolf Hitler had come to power , the Poles decided to prepare themselves for a war . Upper Silesia was the most important industrial region of the country and its defence was crucial . Construction . Major works on the fortifications did not begin until 1933 , when headquarters of the Polish Army decided to take advantage of a proposal provided by General Jozef Zajac , who then was commandant of the 23rd Infantry Division . Zajac suggested that a large number of smaller bunkers should be built , connected with each other by trenches . However , it was decided that nine so - called points of defence would be constructed , each of them made of a few bunkers . These points were : All fortifications were divided into three parts : First stage . Between 1933 and 1935 , the Poles constructed three isolated points of defence - Dąbrowka Wielka ( 1933 ) , Szyb Artura ( 1934 ) and Bobrowniki ( 1935 ) . Altogether , they consisted of around 25 bunker s . Strategically placed on hills , these fortifications provided good view of the area . Second stage . The second stage began in 1936 , when the Poles completed the point of defence in Bobrowniki , together with barracks . In that year , construction crews activities were concentrated on the so - called Bytom wedge - German territory around the city of Beuthen , which was surrounded from east , south and north by Poland . In 1936 the strongest point of defence was located in the settlement of Lagiewniki . It was connected with additional , smaller points - Kamień , Brzeziny and Maciejowice , which created a continuous line of defence . In 1937 the Poles began construction of fortifications in the city of Ruda Śląska , creating points of defence Godula , Nowy Bytom and Radoszowy . Barracks were built as well as munitions depots and guardrooms . Simultaneously to concrete constructions , Polish Army was carrying out hydrotechnological works . Between 1935 and 1937 , on the northern wing of the area , along the Brynica , a set of dams , ponds , swamps and canals was created , whose purpose was to stop the advance of German armored units . This line stretched from Piekary Śląskie to Świerklaniec near Tarnowskie Góry . 1939 . In the early spring of 1939 , when German troops occupied Bohemia , the Poles realised that the Fortified Area Silesia might be bypassed from the south . Therefore , around Mikołów , new works began , but they never were completed . During Polish September Campaign , the advancing Wehrmacht did not attack Polish fortified positions directly ; instead the Germans broke Polish defence west of Częstochowa and deep in the south . Units of the Polish Army left their positions in Upper Silesia on September 3 , 1939 and withdrew towards the east . Aftermath . Currently , the preserved fortifications are under care of the Society to Preserve Fortified Monuments Pro Fortalicium ( " Stowarzyszenie na Rzecz Zabytków Fortyfikacji Pro Fortalicium " ) from Piekary Śląskie .