Despite the rain which stymied plans some had to spend the day outside, officials said that the evacuation of around 45,000 people by 9 a.m. was successful. It was the biggest such evacuation in Germany since the war.
Some 2,500 fire, police, medical and technical personnel as well as city officials were involved in organising the evacuation. Around 1,000 people spent Sunday morning checking to make sure everyone had left the 1.8 kilometre exclusion zone by 9 a.m. local time.
Bomb disposal experts were able to begin their work on the massive British bomb earlier than expected - and once they had defused that one, then worked on a smaller but more unstable American bomb nearby. After they were successfully defused, a smoke bomb also found in the area was blown up in a controlled explosion, marking the end of the dangerous operation.
The enormous 1.8 tonne bomb, dropped by the Royal Air Force, was only discovered thanks to the unusually low level of the Rhine, due to a severe lack of rain over the last few weeks. It was discovered on November 20, alongside a 125-kilogramme American bomb.
Seven shelters were set up in schools in the city and the surrounding area, with space for 12,000 people.
Early in the morning ambulances evacuate 200 elderly residents of retirement homes. A prison and two hospitals had already been cleared over the last few days. All rail connections to Koblenz were suspended from 7 a.m. and roads leading to the city were closed.
Koblenz was hit particularly hard by aerial bombardments during the war due to its position as an important military centre and transport hub. A bomb disposal in 1999 saw around 15,000 city residents forced to leave their homes.
More than six decades after the war, finding unexploded Allied bombs is still common. Authorities believe there are still some 3,000 bombs buried beneath Berlin alone, and World War II devices are regularly discovered in the capital during construction work.
In June 2010, a 500-kilogramme Allied bomb exploded and killed three sappers and seriously injured two others in the city of Göttingen as they prepared to defuse it.