a spa city. The link to Friedrichshafen completed the laying of tracks around the lake. Once the rail line was completed, it became feasible to market the city as a spa resort. The Weimar Republic and the period of National Socialism The peaceful life in Überlingen was interrupted by the war in 1914, when 145 of its sons died, and 20 were missing in action. In 1918, with the German Revolution and the abdication of Kaiser Wilhelm, Überlingen became part of the Republic of Baden. For some, "the Revolution in the year 1918 came as a peaceful relief," but from 1918 to 1923, inflation overran the city, and many of the pensioners living there fell on hard times. During the period of National Socialism (Third Reich), a sub-camp of the Dachau concentration camp, was established at the outskirts of Überlingen (KZ Aufkirch). From October 1944 to April 1945, its 800 detainees worked in Überlingen, constructing an extensive underground facility, the Goldbach Stollen for the manufacture of military armaments). The underground facility, established in natural caves and tunnels, protected the plant from Allied bombing runs. Of the 800 workers, 168 detainees died in either the cave conversion or a misdirected allied bombing raid. The names of the dead KZ prisoners are listed in the book by Oswald Burger ("Der Stollen") as a memorial. On 22 February 1945, Überlingen experienced its only bombing raid, possibly attracted by the presence of the Dachau sub-camp. In this raid, part of Operation Clarion, seven medium-range B–26 Martin Marauders of the US 320th Air Expeditionary Wing dropped 56 500 pound bombs, 7 of them with delay fuses, on the city's rail yards. The bombers had taken off from the base in eastern France by Épinal and dropped their bombs at about 13:45. The bombs destroyed six residential buildings, and severely damaged 17 others; 38 buildings were slightly damaged. Eleven forced laborers, four members of the military construction crews and five residents of the Upper Station Road 97 are buried in the cemetery in the nearby pilgrim church Birnau. The memorial lies approximately east of the church. Troops of the French army arrived on 25 April 1945, and collected all the arms, munitions and weaponry in the city, to be stored in one of the former guild houses built in the 15th century. On the night of 2 May of the year, a fire destroyed the building