From the RAF Bomber Command website
"27/28 November 1944
341 Lancasters and 10 Mosquitos of Nos 1 and 8 Groups
despatched to Freiburg. 1 Lancaster lost.
Freiburg was not an industrial town and had not been bombed before by the RAF.
It was attacked on this night because it was a minor railway centre
and because many German troops were believed to be present in the town;
American and French units were advancing in the Vosges,
only 35 miles to the west.
The marking of the medium-sized town was based on Oboe
directed from caravans situated in France.
Flak defences were light and 1,900 tons of bombs
were dropped on Freiburg in 25 minutes.
Photographs showed that the railway targets were not hit
but that the main town area was severely damaged."
Oboe was a radio navigational system using two, separated transmitters
(the caravans in France) which measured a signal's round trip time
and thus the distance to and position of transponders on the Mosquito Pathfinder bombers.
Supposedly Oboe was very accurate, despite the fact that the railway targets were not hit.
The Mosquito, by the way, was made of wood
and should have been hard to see with the German radar of the time.
An early form of stealth bomber.
Fortunately, for Ms Lust, the Münster and all posterity
the stained glass windows of the cathedral had been removed for their safety.
The open stone lattice work of the cathedral reduced its risk from blast waves
and the medieval use of lead ties to hold the spire blocks together
allowed them to absorb the vibration.
Note the two columns in the market place in front of the Münster.
They stand there today.