The German admirals were only too conscious of the ever-present menace of the British Grand Fleet. Although the distance from Brest to Terschelling was 575 miles it was only 450 miles from Scapa to Terschelling—125 miles shorter. If the Royal Navy received warning as soon as the battleships sailed they would have plenty of time to mass an annihilating battle fleet.
But would the British commit them? Two months before, as Saalwächter had pointed out in his report, they had lost two battleships by risking them too close inshore off the coast of Malaya. The lesson of the sinking of these two battleships on 10 December 1941, 400 miles from the nearest Japanese airfield, was not lost upon the Germans. They did not regard it as a happy omen for their three heavy ships which would be sailing along the English Channel for eleven hours. Yet they decided to risk their ships through the Straits in daylight, even though at the narrowest point they would be less than 100 miles from London.
It was a carefully calculated decision. One particular advantage was that during a night passage of the Straits the Germans would be without effective fighter cover and the anti-aircraft defences would be much less effective. They feared the night attacks of British MTBs or torpedo bombers such as had crippled the Bismarck. In daylight Galland's Luftwaffe umbrella might be able to fight off the RAE Also the battle squadron's heavy fire power would be helped by the massed escort vessels to put up a savage curtain of fire against torpedo and bomber attacks. The most daunting factor was that as they sailed in daylight along the Western Channel towards Dover they would be in an area criss-crossed, by British air patrols. Their presence would quickly be revealed.
While the Germans went about their preparations with meticulous thoroughness and secrecy, the British, not really believing the Germans would attempt it, made some efforts to counter a channel break-out.
During January, a stream of RAF Fighter and Coastal Command reports told of destroyer and E-boat flotillas passing through the Channel in the direction of Brest and a great deal of mine-sweeping along the French coast. They had spotted Ruge's flotillas;. One report said, "The Scharnhorst and Prinz Eugen can be expected to sail from Brest any time after 24 January. Gneisenau is not fully seaworthy and cannot sail until about the end of January." In other words, they not only had ample warning but even calculated the possible time of a break-out.
As a result of these reports, what precautions did the Royal Navy take to see that the Scharnhorst and Gneisenaus hiding-place was turned into a trap? Their "iron ring" of submarines, on watch outside Brest waiting for a chance to torpedo the ships if they ventured from the harbour, had already been withdrawn. It was replaced on 29 January by two 440-ton old-type submarines, H.50 and H.34, which were ordered to patrol thirty-fifty miles away from the port along what was considered the most likely escape route — into the Atlantic. Two days later H.34 broke down and returned to Falmouth. On 1 February her place was taken by H.43. Twenty-four hours after the two H-Class submarines had taken up their patrol positions, RAF spotter planes reported great activity among the German ships.
On 2 February the RAF estimate was remarkably accurate when it said: "There are possibly five large and five small destroyers at Brest. The short cut; for the German ships is via the English Channel. It is 240 miles from Brest to Cherbourg and another 120 miles from Cherbourg to the Dover Straits. Ships can make the passage from Brest to Cherbourg, or from Cherbourg to the Dover Straits in the same dark period, but cannot make the complete passage from Brest to the Dover Straits in one dark period.
"This passage up the Channel seems hazardous for the Germans. However, as their heavy ships are not fully efficient, they might prefer such a passage, relying for their security on the destroyers and aircraft, which are efficient, and knowing full well that we have no heavy ships to oppose them in the Channel.
"We might therefore find the two battle-cruisers and the heavy 8-inch cruiser with five large and five small destroyers, also say, twenty fighters constantly overhead proceeding up the Channel. To meet this sortie we have about six MTBs at Dover, but no destroyers with torpedo armament.
"Our bombers have shown that we cannot place much reliance on them to damage the enemy, whilst our Coastal Command torpedo-bomber aircraft will not muster more than nine.
"Taking all factors into consideration, it appears that the German ships can pass east up the Channel with much less risk than anticipated."
Although Hitler did not know how ill-prepared the British were, this RAF report coincided with his view.
Exactly as the British High Command predicted, the battle squadron would consist of Scharnhorst, Gneisenau and Prinz Eugen, escorted by six large destroyers. After passing Cherbourg and entering the narrow Channel, two E-boat flotillas of ten boats would join them. Off Cap Gris Nez at the entrance to the Straits of Dover, twenty-four more E-boats, with gunboats and mine-sweepers of the Western and Northern naval commands, would bring the total up to sixty-three ships.
The six German destroyers in this formidable fleet were heavily armed modern ships compared with the six small, slow British destroyers available to intercept them. The German E-boats were also faster and more manoeuvrable boats than British MTBs — and they outnumbered them three to one. And the German fighter umbrella of 250 planes was ready to deal with the RAF
Yet the German Navy was not optimistic. They accepted the risk of losing one battleship and possible serious damage to another.
It could easily have happened. As a result of the RAF report on 2 February, Admiral Sir Max Horton, Flag Officer commanding submarines, sent a top secret message to the two submarine commanders saying: "Most secret source indicates enemy ships in Brest are ready to sail." The Admiralty also signalled: "Admiralty now appreciates most probable course of action of enemy ships at Brest will be to break eastwards up the Channel and so to home waters."
In the first week in February, Rear-Admiral Power, Assistant Chief of Naval Staff (Home Operations), who maintained liaison between naval and air planners, talked to Sir Philip Joubert, Chief of Coastal Command. They were both convinced the Germans would come up the Channel, entering the Dover Straits during darkness. Admiral Power drove to give these views to Vice-Admiral Bertram Ramsay, C-in-C Dover. Admiral Ramsay shared the view that the Germans would reach the Straits of Dover in darkness — probably about two hours before dawn. Admiral Power reported this to First Sea Lord, Sir Dudley Pound.
Then came more reports by Hudson reconnaissance aircraft crews of further large-scale mine-sweeping operations by Ruge's flotillas along the Channel. This decided Sir Philip Joubert to give warning. On 8 February in a Coastal Command appreciation, he wrote: '"There are four large destroyers and a number of small motor torpedo boats and minesweepers in Brest. There are indications that the number of destroyers may be increased. During the past few days all three big ships have been carrying out exercises in open waters and should be reasonably ready for sea.