The actual gun was found within days by the French air reconnaissance aviator Didier Daurat. The Paris gun emplacement was dug out of the north side of the wooded hill at Coucy-le-Château-Auffrique. The gun was mounted on heavy steel rails embedded in concrete, facing Paris. The Paris gun was used to shell Paris at a range of . The distance was so far that the Coriolis effect—the rotation of the Earth—was substantial enough to affect trajectory calculations. The gun was fired at an azimuth of 232 degrees (west-southwest) from Crépy-en-Laon, which was at a latitude of 49.5 degrees north. Between 320 and 367 shells were fired, at a maximum rate of around 20 per day. The shells killed 250 people and wounded 620, and caused considerable damage to property. The worst incident was on 29 March 1918, when a single shell hit the roof of the St-Gervais-et-St-Protais Church, collapsing the roof on to the congregation then hearing the Good Friday service. A total of 91 people were killed and 68 were wounded. The gun was taken back to Germany in August 1918 as Allied advances threatened its security. No guns were ever captured by the Allies. It is believed that near the end of the war they were completely destroyed by the Germans. One spare mounting was captured by American troops in Bruyères-sur-Fère, near Château-Thierry, but the gun was never found; the construction plans seem to have been destroyed as well. Under the terms of the Treaty of Versailles, the Germans were required to turn over a complete Paris Gun to the Allies, but they never complied with this. In the 1930s, the German Army became interested in rockets for long-range artillery as a replacement for the Paris Gun—which was specifically banned under the Versailles Treaty. This work would eventually led to the V-2 rocket that was used in World War II. Despite the ban, Krupp continued theoretical work on long-range guns. They started experimental work after the Nazi government began funding the project upon coming to power in 1933. This research led to the 21 cm K 12 (E), a refinement of the Paris Gun design concept. Although it was broadly similar in size and range to its predecessor, Krupp's engineers had significantly reduced the problem of barrel wear. They also improved mobility over the fixed Paris Gun by making the K12 a railway gun.