Why did the RAF bomb cities?

Transcript
Letter from Churchill on area bombing, 1st April 1945

Catalogue ref: CAB 120/303

TOP SECRET
10 Downing Street,
Whitehall.
PRIME MINISTER'S
PERSONAL MINUTE

SERIAL No D.89/5
GENERAL ISMAY FOR C.O.S. COMMITTEE.
C.A.S. (copy sent)

It seems to me that the moment has come when the question of the so called "area bombing" of German cities should be reviewed from the point of view of our own interests. If we come into control of an entirely ruined land, there will be a great shortage of accommodation for ourselves and our Allies: and we shall be unable to get housing materials out of Germany for our own needs because some temporary provision would have to be made for the Germans themselves. We must see to it that our attacks do not do more harm to ourselves in the long run than they do to the enemy's immediate war effort. Pray let me have your views.

W.S.C.
1.4.45