An hour after receiving the signal a Dornier bomber, with its searchlights switched on, came swooping down to 200 feet. As the beams lit a pathway through the water ahead of Sealion, Colvin and his crew scrambled down the conning-tower hatch-way and the submarine dived. But he had been spotted. An hour later, as he lay underwater near Whistle Buoy, depth-charges made Sealion rock and shudder, but they were not near enough to damage her. When the propellers died away Colvin sailed submerged farther out to sea.
What other preparations did the British make, apart from Colvin's solitary submarine, to prevent the Germans steaming up the Channel? First they gave the possible break-out the code name "Fuller." On receipt of this code-word, all available forces would be alerted.
But what forces? Since the First Sea Lord Sir Dudley Pound had decided not to engage with capital ships, his preparations were barely adequate. If they came, he believed the RAF would bomb them to the bottom as the Japanese planes had done to the Repulse and Prince of Wales. It seemed to be overlooked that heavy bomber crews, used to attacking targets at night from a great height, were not trained for accurate bombing of ships steaming at thirty knots and taking evasive action. It was the most formidable bomber force the world had yet seen. But it still could hardly hope to hit fast-moving ships at sea.
The main fighter opposition to the Luftwaffe was Number 11 Group, consisting of Kenley, Hornchurch, Debden, Biggin Hill and Tangmere wings. Their jpb was to protect the bombers against the escorting Luftwaffe umbrella.
The only planes which had much chance of damaging the big ships were torpedo carriers. The British had two types of these — the Fleet Air Arm's Swordfish and the RAF's Beauforts.
The most experienced squadron of Swordfish was 825 which had helped to sink the Bismarck. After the Bismarck operation, 825 Squadron reformed at Lee-on-Solent in December 1941. They had only six Swordfish, seven pilots, six observers and six air-gunners. Only two of the pilots and four of the observers had had operational experience. The air-gunners alone were fully trained and operational. One of them, Leading Airman A. L. "Ginger" Johnson, had won the Distinguished Service Medal for the Bismarck attack.
The leader of the half-squadron of six Swordfish was Eugene Esmonde, a 32-year-old Irishman from Drominagh, Tipperary. Before the war he had been a pilot with Imperial Airways, a forerunner of BOAC. In April 1939 he joined the Fleet Air Arm with the rank of Lieutenant-Commander and was posted to Lee-on-Solent, the Fleet Air Arm's base near Portsmouth, to take command of a Swordfish training squadron.
He was a short man — only five feet six — who was one of the Navy's most experienced and successful pilots. He also had the quality of firm leadership. He never barked brusque words of command, keeping his orders to a minimum and giving them in a quiet voice. If his aircrews were not actually on duty, he did not care what they did — they could creep up to London for a few hours if they wished when they were not wanted. This made the aircrews — most of them at least ten years younger than he was — feel that, however hazardous the operation he asked them to do, they could not let Esmonde down.
He was, of course, a much more experienced pilot than any of them. One of the troubles was keeping up with him. He could fly flat out in a Swordfish loaded with a torpedo, whereas none of them would dare in case they overturned it.
These single-engined biplanes — the Royal Navy's only torpedo bombers — were designed like First World War aircraft. They had a fabric fuselage stretched across light metal struts and open cockpits. They carried a crew of three — a pilot, and observer, and a rear-gunner manning a Vickers machine-gun on a swivel mounting.
Yet these old planes could absorb tremendous punishment. Anti-aircraft shells passed through the fabric instead of exploding against it, as they did with more modern metal fuselages. But the "Stringbags" — as the Navy affectionately called them — had a top speed of only ninety knots, which made them sitting ducks in daylight.
During January, Esmonde was trying to bring his new aircrews up to operational standards, carrying a rigorous training programme in mock torpedo attacks at Lee-on-Solent. It seemed inconceivable that the Admiralty would allow 825 Squadron to remain at half-strength. He waited daily to hear news of another six Swordfish and more aircrew arriving. None came.
In the first week in February, as part of Operation Fuller, the six aircraft were transferred to Manston in Kent to lead the attack on the Brest ships if they tried to force the Straits of Dover at night.
The six Swordfish flew from Lee-on-Solent to Manston in a blizzard, and landed on an airfield covered with frozen snow. When he arrived Esmonde told Wing-Cdr. Tom Gleave, the station commander at Manston, "I shall need a month to get my chaps trained." Next morning the maintenance crews, commanded by Observer Edgar Lee, arrived in lorries from Lee-on-Solent.
Then Esmonde, with RAF squadron commanders, was ordered to a special briefing given by senior officers from the Admiralty and Air Staff. They were told, "We believe that an enemy dash up the Channel is imminent. We believe also that he will attempt to run through the Straits of Dover under cover of darkness about two hours before dawn when tides and high-water levels will be most favourable. There is only one way we can prevent this and destroy him — by throwing in the greatest available torpedo fire-power by combined air and sea attacks. It is intended, therefore, that the Swordfish of the Fleet Air Arm and Coastal Command Beaufort torpedo bombers should stand by to support light naval forces for this purpose.
"It will be pretty fierce when it starts. But with the protection of darkness the Swordfish should have a chance of delivering their attacks and getting away. We want the big chaps crippled so that heavier forces can sink them at will."
Later a signal arrived for Esmonde saying, "The squadron commander to operate only those crews which he considers would contribute to the achievement of the object." He received this message with a wry grin, for he had barely enough fully trained aircrew to fly his planes, and half of them had never seen action.
As the Admiralty never considered the German battleships would ever try to pass the Straits in daylight, Esmonde continued to prepare for a night attack. In conjunction with Wing-Cdr. Tom Gleave, he worked out a tough training programme for low-level torpedo attacks. His inexperienced aircrews needed as much practice as they could get.
Apart from the six Swordfish, the only effective air weapon which could sink or cripple the battleships were Beaufort torpedo bombers. They were a much more formidable aircraft, being able to fly twice as fast as the Swordfish.
Three squadrons were available under the command of Sir Philip Joubert, Chief of Coastal Command. One of them was No. 43 Squadron of fourteen Beauforts, stationed at Leuchars in Scotland, whose main task was to help the naval operation against the German battleship Tirpitz in the Norwegian fiord.
Following the Coastal Command appreciation, Joubert ordered these Beauforts from Leuchars south to Coltishall near Norwich. The decision was correct but bad luck intervened. For three days heavy snowfalls prevented them flying. There were also the usual "administrative delays" — in other words, ground inefficiency. Although Joubert ordered the Leuchars squadron south to meet the urgent threat, he made no effort to plan for his torpedo bombers to attack together.