led to low river levels in the Rhine in December 2011, exposing a 4,000-lb HC bomb in the riverbed near Koblenz. A radius of around the bomb site (containing about 45,000 people) was evacuated while the bomb was defused. Another unexploded blockbuster was found in Dortmund in November 2013, requiring the evacuation of more than 20,000 people from the area. Other bombs were found and defused in Vicenza on 29 April 2001 and 25 April 2014. In 2001, defusing operations required the evacuation of 70,000 within a radius of , while in 2014 defusing operations required the evacuation of 30,000 within a radius of . On 19 December 2016, a British bomb identified as a 4,000-lb HC "blockbuster" was discovered in Augsburg, Germany. It was defused on Christmas Day, requiring evacuation of more than 54,000 people within a radius of 1.5 km. On 29 August 2017, another British HC 4000 bomb was discovered during construction work near the Goethe University in Frankfurt, requiring the evacuation of approximately 65,000 people within a radius of . This was the largest evacuation in Germany since the Second World War. On 8 April 2018, an HC 4000 bomb was discovered during gardening jobs in Paderborn, near the local university, leading to the evacuation of 26,400 people while the bomb was defused. Bombs 2,000-lb HC Design of a 2,000 lb to meet requirements of similar size to existing 1900-lb GP bomb was by Vickers with parachute arrangements by the RAF; this was at the same time Woolwich was designing the 4000lb bomb. Actual case construction was by Great Western Railway Company. Live tests began at start of 1941; a few were used operationally in late 1941 with parachute dropping and delay timer. The parachute requirement was dropped and from early 1942 they were used with conventional tail. Improved Mark II and Mark III (with different fuse positions) followed in 1943. Actual weight was for Mark II and III with 71% charge to weight filling of 60/40 or 50/50 Amatol, RDX/TNT 60/40, or Torpex 2. 4,000-lb HC Mark I: first production design Mark II: three nose pistols Mark III: no side pistol pockets Mark IV: no stiffening beam Mark V: U.S. production Mark VI: U.S. production Filling was Amatol, RDX/TNT, Minol, or Torpex. In 1943, 25,000 of these were used; this rose to 38,000 in 1944. In 1945 up to the end of the war a