Unit Creation Upgrades
 

Research new fortification types

Rapid development of artillery resulted in fortification revolution. Old walls and towers could not withstand artillery fire. Ultimately it was necessary to revise principles of fortification. Now walls were made much thicker; towers became larger and lower, on a level with the wall. Then towers changed into round roundelles or basteas. Casemates inside them played a part of defunct machicules (overhangs on the walls) - shooters fired on the enemy below through the holes in the casemate floor. Ditch and rampart gained new meaning. A rampart protected the foot and the major part of a wall from cannonballs. However, there was a blind space in front of a roundelle because it was round; thus roundelles soon gave place to pentagonal bastions. A wall between bastions was called a curtain. To provide additional defense, they placed fortifications - ravelins and tenailles - in front of curtains.