at six o'clock in the morning. A number of buildings caught fire, including the main guardhouse, monastery building, and parts of St. Peter's Church. One hundred and twenty-one houses in the town centre below the citadel were also destroyed. The French didn't surrender, but there was an extended truce and at the beginning of January 1814, the city of Erfurt was handed over to the Prussians, although the French troops remained in the Petersberg and Cyriaksburg citadels. When Paris was captured by allied troops in April 1814, the Napoleonic troops still remained in Petersberg citadel. It was not until 5 May 1814 that French General Alexandre d'Alton surrendered and handed the citadel over peacefully to the Prussians. Prussian rule (1814–1871) When the Prussians took back the citadel in 1814, they began a new building phase which lasted until 1868. They wanted to make the fortress "bomb proof", and resilient to the strength of the latest weapons. During this period they built the Defence Barracks, the fortress bakery, wells, latrines, and caponiers. A caponier is part of a fortification built in a ditch to provided covered defence to the ditch and/or access to outer parts of the fort. German Empire (1871–1918) After German Unification in 1871, Erfurt became part of the newly created German Empire. The threat to the city from its Saxon neighbours and from Bavaria was no longer present, so it was decided to dismantle the city walls. Only a few remnants remain today. In June 1873 Emperor Wilhelm I gave orders for the Petersberg and Cyriaksburg citadels to be pulled down, but due to lack of funds this was mostly not done. Two ravelins (Peter and Wilhelm) and the hornwork along the walls were removed. An access road was built and Lunette I was demolished and Lunette II and Ravelin Gabriel were reduced in height. The rubble was used to fill in the ditches. Prior to World War I there was a renewed interest in the strategic military location of Petersberg Citadel. New buildings, such as workshops, warehouses, barracks and a military detention centre were built between 1912 and 1914. Post World War I The fortress remained an important garrison position until the end of the war in 1918. After World War I, as a result of the Treaty of Versailles in 1919, there was a gradual abandonment of military facilities during the Weimar Republic period. Petersberg was