Early castles were designed to withstand short sieges, with the understanding that help from a more powerful overlord would be on its way. They were not designed to handle the type of physical assaults that later castles suffered. In this period, they were all basically designed as motte-and-bailey layouts, but some had leveled off the motte, replaced by a stone keep. The bailey was still an integral part of the defense.
An attack on this kind of castle began with the attempt to break through the outer wall. This wall was far enough from the keep itself that fighting at the wall did not directly threaten life inside the keep. Where the bailey wall came near to the keep, there were usually natural features like cliffs or rivers to make it harder to attack at that place.
Although the main farmland was outside the bailey, the large area (possibly several acres) enclosed by the wall had enough garden and stabling land that people could get by for a period of time. In a siege, many of the farmers outside the bailey would bring their produce in a wagon and camp inside the bailey yard with their families, assuming they had warning of the attack. The bailey housed many horses as well as food-producing farm animals. Doubtless, it also had a number of wooden outbuildings, workshops and cottages, that could be destroyed if sieges broke through.
If it looked like the siege was going to break through the walls, storage and people moved into the cramped tower keep. It was often designed with no ground-floor entrance, which must have made it difficult to haul in large casks or sacks. A wooden stair ran up the side of the keep to a door opening on the second floor. Below this level, there were no windows or doors. When a siege moved inside the bailey walls, the wooden stair was set on fire so that nobody could go in or out.
There were windows at the second-floor level, but they tended to be few, narrow and designed for defense. The one exception might be windows looking into the Great Hall, where most daytime business was carried out. They needed daylight, but at the same time, while glass was still scarce, large windows were also a cold-weather liability.
The top floor had the most windows, since it was unlikely that attackers could make ladders that tall. The roof of a tower keep was always flat and formed a walking surface. Early towers had turrets around the top, so that defenders could hide while shooting through the gap. The corners often had taller towers for better visibility.
More elaborate defensive mechanisms were not yet in use, because the basic idea of defense was to hold out long enough for the regional duke or king to come with a larger army. Just making the house difficult to attack, by having a guarded wall and no ground-floor entrances, was enough to discourage less deliberate attacks. Most castles were never attacked; just being a castle was enough to maintain them as safe seats of regional government.
The rooms inside, especially on the upper levels, were often furnished as nicely as the people could manage. They painted the inside walls, often with murals or flower designs. But most of the rooms were inescapably cold in winter, since fireplaces and chimneys had not yet been invented. The Great Hall was on the second floor, which meant it was supported by timbers. Fire pits for its use had to be built carefully so that the floor didn’t weaken or catch fire. Smoky air was a constant problem.
Latrine chutes were built into the outer walls. Sometimes the latrines hung out over the wall by a little bit, allow waste to drop directly to the ground. One of the dangers of enclosed latrine chutes was that a determined enemy might find a way to climb the wall inside the chute, where guards could not see the attackers until it was too late.
The castle’s aristocratic family probably spent only a few months per year actually living in the castle. They usually had more than one castle and needed to rotate among them to take care of regional government. Manor houses on farms were undeniably more comfortable than these early castles, so they probably included some houses in their annual rotation.