In fact Hitler's thrust against Britain in the Mediterranean Sea in the winter of 1940-41 did not take place in France any more than in Spain. It took place in the eastern end of the Mediterranean Sea, where Mussolini's armies were suffering defeat in both Greece and northern Africa. On 10th December, 1940, Hitler undertook to send German air units to southern Italy, for a limited period only, to attack British ships passing between Sicily and the northern African coast, or even, if the critical situation in the Mediterranean Sea required, in the Ionian or Aegean Seas. As Germany was not at war with Greece, no action was to be taken against Greece for the time being. But three days later Directive No. 20 showed that this abstinence was to be very temporary. Britain was assisting the Greeks against Italy, and it was essential to Hitler, if he could not crush the British altogether, at least to deprive them of any foothold in Europe.