Medieval castles were structures that were used in medieval Europe from the 11th century onward. Although castles had existed in some form for many centuries, it was in the 11th century that they were actively used for military campaigns and fortifications.
Medieval castles were formidable structures that could house a large number of soldiers or knights as well as the local populace. Castles also used features like moats and ditches to reinforce their defenses. From the 11th to 16th centuries, medieval castles underwent a significant evolution.
The earliest castles in Europe existed as early as the 2nd century. By the 9th and 10th centuries, confirmed historical records mentioned castles exist. At the time, castles were usually built in Frankish lands, previously a part of the Carolingian Empire.
The early castles were simple structures of stone that were large enough to house an army and protected the lord of the castle from various external threats. Most of these castles were simply enlarged residences of the powerful lords and other members of the nobility. In many regions, a lord required the permission of the monarch to build a castle.
The purpose of a medieval castle was manifold. The primary purpose was that of defense. A castle could very effectively shield its inhabitants from an attacking force. With its various features, a castle also made it possible to repulse any direct attacks on it. Another purpose of a castle was that it served as the residence of a lord and his household. It also provided a home for the standing army of a lord, such as the knights in his retinue.
Motte-and-bailey castles were commonly used from the 11th century onward. The motte was basically a large hill on top of which a wooden keep was stationed. The keep housed the residents and animals of the castle. The bailey was located at the foot of the hill and housed troops. It was protected by a wooden palisade.
Other types of castles used in the High Middle Ages were stone keep castles. Stone keep castles were an evolution of the motte-and-bailey castles. They comprised of a stone keep with thick walls at the center which in turn was surrounded by the outer walls of the bailey. Concentric castles comprised multiple layers of walls which offered the best protection against external attacks.
From the 11th century onwards, castles came to be actively used in military offense and strategy. The Normans in particular used castles during their successful conquest of Anglo-Saxon England in the mid-11th century.
They specifically utilized motte-and-bailey castles to consolidate their conquests in England, station troops in different areas, and establish permanent fortifications to subdue any chances of rebellion. During this period, castles were also used elsewhere in Europe for defense and for the residential needs of the powerful lords.
From the 14th to 16th centuries, medieval castles underwent a significant evolution. During this period, a central stone keeps lost all its importance so it was altogether abandoned as a permanent feature of castles. Instead, most of the focus was shifted to the outer curtain walls and their defense.
For this purpose, concentric walls and various features in the curtain walls were introduced. This evolution sped up with the advent of gunpowder which created a need for outer walls to be able to withstand cannonballs. This was achieved by building thicker walls, more curved towers, and niches in the walls for the castle’s own guns.
During the late medieval period, the use of castles as the residence of a lord had almost become outdated. Instead, castles were almost entirely used for military purposes, with some notable exceptions. The monarchs, however, continued to use castles throughout Europe. The chief purpose of the castles during this period was military use. For this reason, castles significantly grew in their size during this period and were often sizable enough to house large armies.
The Norman period was immensely important in the history of English castles. This is because Normans were the first who introduced proper castle structures in England. They first began the use of motte-and-bailey castles during their conquest of Anglo-Saxon England in 1066. It was these basic castles, with their hill-mounted motte and palisade-surrounded bailey structures that paved the way for the subsequent stone keep and concentric castles.
The Norman need to build castles and then evolve their design to subdue an Anglo-Saxon England which rebelled times and again. Successive Norman kings would go on to lead entire Europe in terms of the size and sophistication of the castles they would build.
From the 16th century onwards, the use of castles began to decline so that they became military irrelevant. Very few new castles were constructed after this period.
From the 16th century onwards, the construction and use of castles saw a clear decline. The main cause behind such decline was the advent of the age of gunpowder. Large guns which could propel heavy cannonballs at very high speeds could easily wreck damage the best of castle walls.
In contrast, layers of closely packed dirt could withstand the impact of cannonballs better. As a result, castles declined in their military significance. They continued to be used in a limited capacity, as residences of monarchs and other members of the aristocracy.
In military terms, castles gave way to forts, as in colonial North America. Forts comprised of earthen ramparts which were far more effective in withstanding cannon fire.