The Battle of Britain Five Months That Changed History, May—October 1940 by James Holland (z-lib.org).epub

England. Beforehand, the Führer had made it clear that he preferred an
economic blockade and naval and air attacks to bring Britain to her senses.
Nonetheless, Raeder had ordered a preliminary investigation into the
feasibility of an invasion the previous November. So, too, as it happened,
had OKH. For now, though, Hitler told Raeder not to think in terms of
invasion, but to continue the economic blockade and to intensify naval
warfare against the British Isles. In a directive a few days later, the
Luftwaffe was given ‘unlimited freedom of action’ against Britain just as
soon as sufficient forces were available. The Naval Staff certainly
welcomed these directives. They ‘indicate clearly the object of this war’,
noted the OKM War Diary, ‘the annihilation of the main enemy, England.
The way to her defeat lies through the destruction of France, her
Continental sword, to the starvation of the British island empire and to the
ruination of her economic fighting power.’
In the meantime, Hitler needed to finish off France, Belgium and the
British forces there. Late on the 21st, Guderian at last received orders to
continue his advance, now in a northerly direction with the capture of the
Channel ports as his objective. This did not begin in earnest until the 23rd
because the day before, 1st and 2nd Panzer had been ordered to secure the
Somme bridgeheads and wait for the rest of von Wietersheim’s mechanized
divisions to catch up from Sedan, but the following day, in lovely earlysummer
sunshine once more, each of Guderian’s panzer divisions was
beginning its assault of the key Channel ports of Boulogne, Calais and
Dunkirk. 10th Panzer, briefly taken out of his command the day before, had
now been handed back once more, and so he ordered it to press on to Calais
while 2nd Panzer attacked Boulogne and 1st Panzer made straight for
Dunkirk, a mere twenty-five miles to the north-east. Three divisions, three
towns. The arithmetic was very simple.
Guderian had good reason for optimism, even though the British troops
trapped in Boulogne and Calais were fighting fiercely. Soon all three ports
would surely be in German hands. And once that happened, there would be
no chance of escape for the French, Belgian and British troops trapped in
the encirclement.
Since the Allied commanders barely knew exactly what was going on half
the time, it was not surprising that most on the ground had only a sketchy
idea of what was happening, most of which was fed by rumour after