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              |  High walls gave those inside a castle a tremendous
                  advantage.
 
 
 Walls
 At first castle walls were wooden, making them cheap and quick
                  to build, but they were vulnerable to arson. Stone walls
                  followed, and with each generation they grew thicker and
                  taller. From the mid-13th century, many castles had concentric
                  rings of walls, one encircling the other. Caerphilly Castle is
                  the earliest example of this in Britain, and the largest
                  castle ever built in Wales. Low outer walls served as barriers
                  against siege towers and battering rams. If attackers managed
                  to break through this outer ring of defense, castle defenders
                  could retreat behind high inner walls.
 
 Corner towers stood out from the walls, giving defenders a
                  better perspective on enemy movements. Windows were rare;
                  instead, slits called loopholes were built for archers.
                  Sometimes builders thickened walls low to the ground to
                  protect them from battering rams. Often, these walls sloped
                  away at the base to redirect objects dropped from the top of
                  the castle wall, ricocheting them out at soldiers on the
                  ground.
 
 Because they had walls to protect them, castle defenders would
                  sometimes hunker down and try to wait out their attackers.
                  Those inside made sure they could be self-sufficient when cut
                  off from the outside world by a siege. They built wells and
                  kept livestock inside their walls, guaranteeing fresh water
                  and fresh meat during a siege. They also salted foods such as
                  bacon and fish and stored grains and beans by the barrel-full.
 
 Castle garrisons also stockpiled weapons, for reinforcements
                  often could not get through. If a siege continued into winter,
                  castle dwellers had more protection from the elements than
                  attackers, and if their rations held up, also more food to
                  sustain them.
 
 Those besieged inside a castle often negotiated time frames
                  for surrender with the enemy. For example, a castle garrison
                  might tell an attacking army that they would surrender if
                  reinforcements did not appear by a specified date. This would
                  save lives on both sides and avoid the steep financial costs
                  of a siege as well.
 
 
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