12. Faced with this situation the Allied forces in Belgium were driven into a hurried and harassed retreat in which the German superiority in both armour and aircraft gave every advantage to the enemy. Coordination between the British and French armies was the result of long preparation, that with the Belgians was an improvisation. The speed of the German advance soon took them across the communications of the British forces with their main base port of Le Havre, while the efforts of the British and the French to counter-attack and cut off the German spearhead were doomed to failure from lack of resources. The surrender of the Belgian Army left the British left flank undefended, and for many days the destruction of the whole British Expeditionary Force seemed a probability.