to rejoin Force A; they sailed late on 4 April. Hermes sailed from Trincomalee and was ordered to hide northeast of Ceylon. The Japanese did not perform an aerial reconnaissance sweep along their intended course on the afternoon of 4 April, and a planned reconnaissance of Colombo harbour by cruiser floatplanes was cancelled. The Japanese realized surprise was lost after intercepting a signal from Colombo asking QL-A to repeat its report. Attack on Colombo Japanese intelligence on the morning of 5 April 1942 indicated that British carriers were absent, and the Japanese morning air search was limited accordingly. At dawn, Japanese aerial reconnaissance aircraft flew off to the south-west and north-west; they would fly out to a maximum of over the next few hours. A reconnaissance Fulmar launched from Force A at 08:00 spotted one of the Japanese aircraft at the extreme edge of the south-west search area at 08:55 about ahead of Force A. Shortly after 06:00 Nagumo's force began launching 91 bombers and 36 fighters for the strike on Colombo. British early warning failed to detect and identify the incoming strike, forcing British pilots to scramble under fire when the first Japanese aircraft appeared over them at 07:45. The effective defence of the Ratmalana airbase by British fighters left the harbour exposed. The armed merchant cruiser , the Norwegian tanker Soli and the old destroyer were sunk; three other ships were damaged. The port was damaged but was not put out of action. 20 of the 41 British fighters that took off were destroyed. At least one fighter was damaged and made incapable of flight while attempting to take off. The six Swordfish of 788 NAS arrived during the battle and were shot down. The Japanese lost seven aircraft. Nagumo changed course to west-southwest at 08:30 – unknowingly causing the opposing fleets to steam toward one another – and recovered the Colombo strike from 09:45 to 10:30. The size of the airstrike on Colombo was Somerville's first concrete evidence that the Japanese force contained more than the two carriers he expected. Nonetheless he continued to steam toward the enemy at 18 knots. Radar-based fighter direction would allow Force A to avoid surprise attack by neutralizing shadowing Japanese aircraft. Loss of Dorsetshire and Cornwall At 10:00, an aircraft from Tone searching the southwest area spotted and began shadowing Dorsetshire's force; the aircraft reported that the cruiser was heading southwest