Text: They replaced the old small castles on high ground protected only by wooden stockades with large central fortresses out of range behind broad moats, surrounded by solid stone ramparts and earthworks strong enough to resist cannon fire.
Entailment: They replaced the old castles on high ground which were protected with wooden stockades with large fortresses behind moats and earthworks which would block cannon fire.
Contradiction: The traditional castles were kept as they were but additional ones were also built.