Fortifications, which allowed its access to be independent from the city gates. The citadel was accessible by a main gate turned toward the city and a secondary access leading directly to the countryside.
In certain cases, the citadel was an ancient preexisting castle or an enlarged and fortified residence around which the city developed. It might also be a newly created fortress fulfilling three distinctive roles.
The first role was logistical: The citadel contained everything needed in order to resist a long siege, such as living accommodations; stores of food, water and forage; and arsenals and workshops. It was also a supply point and winter quarters for armies in a campaign, as well as a military, fiscal and administrative center.
Secondly, the citadel was a powerful military bulwark. Just like the keep in the medieval castle, it acted as a final fall-back position, a retreat from which to continue the defense even when the town was conquered.
The citadel was therefore strongly fortified with powerful towers, high walls, and a fortified gatehouse with drawbridge and deep ditches. This display of strength was also intended to deter enemies from laying siege.
The third and most important role was political. The fortress on its rocky height dominated the city and its approach; the town nestled below in its shadow, perpetually reminded of its dependence.
Citadels were often built in the most important cities of realms, duchies, counties or ecclesiastical principalities as residences for kings, dukes, earls or high prelates. These powerful rulers—living on the resources of the nation as a whole—dwelled within splendid palaces with gardens and dependencies. In less important cities where the rulers did not live permanently, the citadel was occupied by royal, ducal or episcopal representatives and governors. In some cases the citadel was intended to subjugate, control and overawe conquered populations of
Questionable loyalty or municipalities with rebellious propensity.
The citadel had its own garrison, loyal to the ruler and ready to repress insurrections, as well as its own civil servants collecting taxes. The garrison might also discourage the inhabitants from surrendering at a premature stage in a siege. Very often the construction and maintenance of the expensive citadel as well as the occupying garrison’s pay were financed by citizens’ money.
For all these reasons, the citadel represented a threat. It was an unpopular, even hated place, an object of terror and dictatorship as well as a financial burden. Consequently, as soon as relationships between the occupiers and the conquered population improved, urban authorities usually asked for the dismantling of the citadel, or at least military takeover of its expenditures.
In Britain the castles built by King Edward I in Wales in the second half of the 13th century were citadels intended to secure his communication lines, to house English garrisons and to submit the rebellious Welsh. In France the citadels were directly linked with the consolidation of the royal power and the territorial expansion which principally begin under Louis XI’s reign (Beaune, Dijon and Auxonne citadels, for example, were built after the annexation of Burgundy in 1577). In the Netherlands, Germany, Spain and Italy, the citadel, respectively called dwangburcht, Festung, alcazaba and rocca, was often both a dwelling place and a fortress occupied by the local ruler.
Citadels played an important role in the 16th and 17th centuries. In the 18th century, however, citadels lost their political role because of the population’s loyalty, and in the 19th century they lost their military function because of the creation of outer rings of detached forts. Today many citadels remain military or civil administrative centers, and some are still palaces occupied by nobility, while others have been turned into prisons or museums.