As is often the case in the English language the noun ‘citadel’ has taken on various meanings and inferences over time. The most common use for the term is to define a fortress (fort), a stronghold, a place of last stand if under threat or invasion and the Hull Citadel certainly fits that context. In some cases it seems it also implied a place to which the local people could retreat to safety as well as any military personnel, it is not clear whether it was ever envisaged that Hull Citadel should provide this but the perimeter walls encompassed quite a large area so it had the potential to do so, although the people would have had to cross the River Hull by the one bridge then existing or be ferried across.
Another implication associated with the word ‘citadel’ is of a structure that dominates the townscape, the two 18th century views of Hull from the Humber Estuary show this to have been the case at Hull. Enemies sailing up the Estuary (as, for example, had the North-men in 1066) would see firstly the imposing south blockhouse and curtain wall before the town itself.
Later the Salvation Army adopted the term ‘citadel’ to define some of their places of worship and in some contexts the word implies a place of glory and goodness, a place of central importance.
In France the Bastille was sometimes referred to as a ‘citadel’ having been built in the early 100 Years War (14th century) as one of a series of forts around Paris to protect the city from English armies (in the same way that Windsor Castle was one of a number of castles built by the Normans around London, again to protect the city from the English!). For most of its subsequent life the Bastille was used as a state prison and armoury. It was demolished during the French Revolution after the ‘storming of the Bastille’, 14th July, 1789. The picture above is of the Bastille and Porte Saint-Antoine from the north-east in 1715-’19 and shows its related earthworks and river-side site (taken from the Internet).