Related Clues:

• Operation by a castle
• Castle-storming strategy
• Persistent offensive
• War strategy requiring patience
• Intense attack on a fort, say
• Sudden all-out attack
• Attack that takes a long time
• Blockade, for instance, European is backing
• Intense assault
• Drawn-out attack
• The type of economics that leads to blockade?
• Attack that requires patience
• Alternative to a blitz
• Campaign that may involve catapults and trebuchets
• Attack involving encirclement