But the shipping losses continued at a serious rate and were regarded by the Government with growing alarm. In February 1941, Western Approaches Command was set up to co-ordinate operations by the RAF and RN in the sea lanes leading to the major ports of Liverpool, Glasgow and Belfast via the North Channel, to which route convoys were now restricted. 15 Group moved into the new Command area, also setting up its headquarters at Liverpool and a new Group, 19, took over at Plymouth to cover the Bay of Biscay area. In March, the Prime Minister issued his famous "Battle of the Atlantic" Directive which called for the main strength of RAFCC to be concentrated urgency in the Western Approaches area.
Action soon followed. For instance, the force of RAFCC fighters at Aldergrove was considerably strengthened by
the presence there during the spring of one and a half squadrons of Blenheims and in early April 252 Sqn arrived
with Beaufighters, the Command's new standard long-range type. The squadron was about to achieve its first 'kill' for, 90 miles west of Ireland.
On 16 April, Irishman Flight Lieutenant Riley in Beaufighter
'K' encountered a Condor which we shot down in flames.
By May, German Heinkel 111 aircraft were also operating
over the Atlantic and on the 28th one of them was shot
down, followed on the 23 July by another Condor.
On both occasions, Hudsons of 233 Sqn were responsible
while on convoy escort.
By July 1941, RAFCC strength had increased to thirty five
operational squadrons, nine of which were in Northern Ireland
at three new air bases as well as Aldergrove. Three were at
Limavady flying Whitleys, Hudsons and Wellingtons
respectively; two were at Lough Erne with Catalinas while at
Nutts Corner a new squadron - 120 was just beginning to form. Also opening for use by RAFCC was a new airfield at Ballykelly, albeit it was not until mid-1942 that operational squadrons were based there. This amounted to the largest number of RAFCC squadrons based in the Province at anytime during the war and yet locally-based aircraft had thus far failed to sink a U-Boat, in contrast to their counterparts in other areas, notably 18 Group.
One reason was the lack of very long range (VLR) aircraft to patrol the 'Gap', a large area in mid-Ocean where U-Boats were operating unhindered by RAFCC aircraft. The VLR types available - American B17 Fortresses and B24 Liberators - had been acquired and flown to Britain months previously but their allocation to RAFCC was delayed because the perceived needs of Bomber Command and the Transatlantic Ferry Service had a higher priority. In the event, Liberators were the first to be released, to 120 Sqn at Nutts Corner where they became operational in late September. Able to remain on station for more than 3 hours at 1100 miles from base, equipped with radar and 8 depth charges, they were formidable aircraft.