In the same time frame, other air forces increased from eight obsolete torpedo bombers, to seven Consolidated PBY Catalina flying boats, 14 Bristol Blenheim IV bombers, and 12 Fairey Swordfish torpedo bombers. On the eve of battle, RAF forces were part of 222 Group, commanded by Air Vice-Marshal John D'Albiac. Raid First moves The Japanese sailed from Staring Bay on 26 March as planned. Somerville sailed on 30 March in expectation of an attack on 1 April, and deployed his fleet in a patrol area south of Ceylon. Ceylon air defences and forces went on alert, with land-based aerial reconnaissance concentrating on the southeast, where the Japanese were expected to approach to launch strikes at Colombo and Trincomalee. Late on 2 April, the British retired toward Port T – southwest of Ceylon – to refuel. Somerville also detached various ships to resume previous commitments; the heavy cruisers and were sent to Colombo, and Hermes to Trincomalee. Air defences stood down, although Catalina patrols continued. At about 16:00 on 4 April, PBY Catalina flying boat (AJ155/QL-A) from the Royal Canadian Air Force's (RCAF) 413 Squadron flown by Squadron Leader Leonard Birchall spotted Nagumo's fleet south-east of Ceylon on a course that would have entered Somerville's previous patrol area from the south. The Catalina transmitted the sighting, but not the size of the fleet, before being shot down. At this time, Somerville was refuelling at Port T; Force A sailed eastward toward the Japanese upon receiving the sighting; Force B could not be ready until 5 April. Catalina FV-R from 205 Squadron RAF took off at 17:45 to shadow the Japanese fleet, making its first report at 22:37 on 4 April, and a final report at 06:15 on 5 April while from Ceylon. FV-R was shot down about 90 minutes after the final report. Within an hour of QL-A's report, D’Albiac met with his subordinates to discuss an anticipated Japanese strike after dawn. 222 Group issued a warning to subordinate units before midnight, and units went on alert at 04:00 on 5 April. On the morning of 5 April, six Swordfish from 788 Naval Air Squadron (788 NAS) began relocating from China Bay, near Trincomalee, to Colombo, in preparation for a strike on the Japanese fleet. Admiral Geoffrey Layton, on Ceylon, ordered ships put to sea to avoid being attacked in harbour. Cornwall and Dorsetshire, which had just reached Colombo, were sent