But meanwhile Europe had been flooded with literature on the subject,
and the whole policy of fortification as well as its minutest details
were discussed _ab ovo_. The extremists of both sides revelled in their
opportunity. Some declared that, with the use of heavy guns and armour,
fortresses could be made stronger than ever. Others held that modern
fortresses were far too expensive, that their use led to strategic
mistakes, and (arguing from certain well-known examples) that
extemporized field defences could offer as good a resistance as
permanent works.
European military opinion generally is now more or less agreed on the
following lines:--