On 17 December, extensive damage was done to the Berlin railway system. By this time the cumulative effect of the bombing campaign had made more than a quarter of Berlin's living accommodation unusable. There was another Main Force raid on the night of 28/29 January 1944, when the western and southern districts were hit in the most concentrated attack of this period. On 15/16 February, important war industries were hit, including the large Siemensstadt area in the west, with the centre and south-western districts receiving most of the damage. This was the largest raid by the RAF on Berlin; the campaign continued until March 1944.