In North Belgium a thrust towards LILLE if successful might cut off Allied troops to the North of this line. In the centre it is as yet uncertain in which main direction the attack is taking place. It may be South-West in order to link up with the advance in the SEDAN area or more probably West and North West to link up with the Northern attack, as a double envelopment. 5. There have been reports from Switzerland that 20 German divisions are concentrated in depth between CONSTANCE and BASLE ready for an attack through Switzerland.