By the peace treaty in 1660, Denmark was amputated by loosing all its provinces East of the Sound, and Copenhagen now became a frontier city. By its situation it might be reached from the new Swedish coast in an hour or two, and strong fortfications became essential.
The Dutch engineer Hendrick Ruse (1624-1679) was sent for, for that reason, to transform the new citadel according to his principles of fortfication. He had in 1654 published a book, "Versterckte Vesting", where he had adapted the old Dutch fortification system: He wanted the flankes of the bastions to be built at obtuse angles to the rampart and have them devided into two - or better: three - storeys to improve the possibilities for enfilading. He also wanted to place a system of outworks between the main ditch and the outer ditch of the fortress. These theories were the basis for severe discussions between contemporary engineers, but Hendrick Ruse got the chance of realizing his theories by his rebuilding of the the Citadel of Harburg, South of Hamburg in Germany in the years 1658-1660 for the duke of Braunschweig-Lüneburg, and in Kalkar near Kleve North of Köln 1658-1667 for the electoral prince of Brandenburg. These citadels gave Ruse the reputation of being the best engineer in the Northern part of Europe at this time and he was in the summer 1661 invited to Copenhagen to advise the Danish government in the matters of fortification. During a short stay he made a plan for the rebuilding or transformation of the citadel with barracks, artillery and provision stores, guardhouses etc., etc. for a permanent garrision.
His project was followed without discussion or reservation. A contract was made only 6 days after his project had been presented to the King. It concerned only the ramparts, but were in 1663 and 1664 followed by new contracts for the barracks, the stores and the foundations of a "royal building".
Before all the projected buildings were completed, the work suddenly stopped. By the turn of the year 1666-1667 Hendrick Ruse rendered the Citadel over to the military administration. At this time the ramparts were in their full extension with five large bastions in the main area including six of the originally sixteen planned barracks, the stores for artillery and provision and the two gates each with small guardhouses. The extended outworks towards the land and the strong counterscarpe to the Sound were also completed.
Large parts of the ramparts still exists, although the flankes of the bastions were simplified as early as in the 1680s. Extensions of the Copenhagen Harbour in the 1890s have cut some of the outworks. All the buildings inside the Citadel are preserved. They have only been slightly altered since the 1660s: The six barracks got mansard roofs during a restauration in the middle of the 18th century, and the artillery store was completely rebuilt in 1824-35, but in the same shape as earlier. In 1703-04 a fine barocco church was added, and in 1725 a house for the commandant were built. In spite of the alterations the Citadel of Copenhagen witnesses of the original state of the Citadel of Hendrick Ruse, as he in 1666-1667 handed it over to the Danish Army, which still use it.
The Citadel of Ruse was originally projected with buildings placed in a symmetrical plan around an East-West axis with barracks placed in a form of a trapezium and with the "royal building" and the church as dominant features placed vis-a-vis each other on both sides of the drillground in the center of the fortress. As architectural specialities the two barracks next to the gates were made shorter just to give room for a little square inside the gate. On the other hand the two barracks West of the main street between the gates were partially placed on the drill ground to frame the view of the church as seen from the West.
The fact that the project for the building was never completed has blurred this architectural visions of Hendrick Ruse. A map made by him around 1662 gives us the opportunity to reconstruct what was never built, but what had certainly been planned.
1. The Gates
The two gates to the Citadel have not changed much since they were built in 1663 and 1664. They differ a little when you see them from the outside, but seen from the citadel itself they were unostentatious buildings with a guardhouse an each side. Each guardhouse had corbelled-out roofs, resting on four posts. These guardhouses were moved a little out from their original situation up to the ramparts in the middle of the 18th century, because they were ruined by moist from the soil, but they were carefully rebuilt in their original form.
Today the gates and the guardhouses stand in pure brick. Originally they were whitewashed in the normal colours for military buildings in Denmark at this time: White walls and red woodwork.
[Note: The parts of the gates placed outside the rampart have not been included in the model. - IR ]
2. The Barracks
In the original plan of Hendrick Ruse 16 barracks were projected, but for reasons we do not know only 6 were built.
Each barrack consisted of a number of identical units, each with 8 rooms. Each room accomodated 8 soldiers, so a unit had room for 64 men. These 8 rooms were placed with 4 on the ground level and 4 on the 1st floor. All 8 rooms had a joint chimney and thus the number of chimneys matches the total number of units in the barracks.
In the plan for the buildings in the Citadel the barracks were to be built in the form of a trapezium. The units of each barrack were square, and in the irregular parts of each barrack (nearest the ramparts) it was intended to place the dwellings for officers of the lower ranks and the craftmen, who worked for the fortress (blacksmiths, wheelrights etc.). These dwellings were not built - to the damage of the architectural pretentions of the Citadel.
The colours are reconstruced according to a drawing from 1680 and other contemporary sources: Whitewashed walls with red woodwork. Since late 19th century the barracks have had red walls and white woodwork.
3. The Storage Buildings
In the Northwestern part of the Citadel a provision store in three storeys was built in 1663. It consisted of three buildings: Two long buildings to the North and the West and a smaller corner building. The situation and importance of the corner building has been emphasized by projecting it a little out from the front line of the two other buildings.
The Armoury was built in 1664 as a counterpart to the Provision Store. The West wing was originally used as brewery and bakery and only the South wing was used for the Armoury. The corner house was originally the prison with small barred windows. In the Western wing - nearest the corner house - were rooms for the prison guard.
The colours of the stores were originally the same as the colours of the barracks: White with red woodwork, but is now red and white like the barracks.
4. The "Royal Building"
Between the two stores a fundament for what was called the "royal building" was laid in 1664, bud the intended building was never built.
It is known from the plans of the Citadel, from archaelogical traces and from contemporary drawings, now at the Collection of the Royal Academy of Fine Arts in Copenhagen. The drawings are undoubtedly made by Ruse. These show a strange four-winged building in the classical Dutch barocco style. The four corners of the building are projected a little out from the walls of the wings - like the corners of the Provision Store and the Armoury, from which they are divided by two very narrow streets.
The "Royal Building" is predominant with its height, which is almost the double of the height of the two storage buildings and three times the height of the barracks. Furthermore the wing in the front towards the drill ground is one third higher than the height of the corner house with a roof terrace with a "belvedere" with a high rounded roof and a spire. In total more than 43 m high.
A sectional view of this part of the building shows that the whole wing was only intended to have two storeys above a low cellar level.
The corner wing and the two wings to the North and the Souch are more traditional with a number of ordinary rooms.
The fourth wing towards the ramparts - and in fact half embedded into these - is even more amazing than the east wing: After the drawings it only was to have windows in the upper storey and no windows or openings at all in the lower parts or in the two corner buildings.
A sectional view of this part of the building gives the impression of a building for a very special purpose: The walls and the horizontal divisions are more than 3 m thick and leave only room for small vaulted rooms with extreme narrow entrances. From the wing a underground stone gallery with storerooms on each side leads to the lower part of the planned powder mill on the Bastion just outside.
This does not harmonize with the character of the bright and representative wing towards East, but nevertheless: This part of the building must have been planned as a magazine for gun powder. Some of the rooms might even have been planned to be a prison for particular dangerous prisoners of the state.
Architecturally the building is a novelty in Denmark in the combined function of castle (or representative rooms) for the royal family, offices, and stores for gunpowder, perhaps with a state prison - a mixing of unexpected purposes that are quite amazing, and no foreign examples seem to be comparable to this building.
5. The Gunpowder Mill
Ruse made more drawings of the mill, which was to be placed on the Bastion of the King just outside the Western wing of the "royal building", where the wind was - and still might be - heavy. It was intended to be built in brick (which was very uncommon for mills in Denmark at this time) on an foundation of a little round fortress with loopholes.
It has cellars in three storeys inside the bastion, with workshops for the powdermakers. To keep the powder dry, the strong walls beneath the surface of the bastion were planned to be built with arial channels, leading to the fresh air outside the mill.
With the underground gallery with store rooms on each side the mill was to be connected to the "royal building". In the west wing of this building more store rooms were probably intended.
6. The Church
On the plan by Hendrick Ruse from 1662 a church was planned at the dominant place vis-a-vis the "royal building" on the eastside of the drill ground. Ruse has not left any drawings of this building, but in the National Museum of Denmark a drawing was found of a church in the same dimensions (length and width) as the church in the Citadel. It bears the monogram of Frederik the 3rd, who died in 1670, and the project and must therefore be from the 1660s. We know no other plans for a church from these years and with a certain hesitation it may be attributed to the plans for the citadel in the mid-1660s.
The drawing shows a gigantic barocco church in a Roman barocco style with a front with a tree-angled pediment. Over the church a hemispherical dome with an ornamental roof is seen and over this a lantern with a golden globe. More globes are placed on each corner of the church.
The German architect Francois Dieussard has been attributed this drawing. He was in Denmark in some months of the year 1668 but without leaving any certain traces. The attribution to him seem therefore unfounded. On the other hand it is not a drawing of Hendrick Ruse. The question of who made this imposing church must therefore stand open.
7. The Vicarage (?)
Around the church Ruse has drawn a three-wing building of which we know absolutely nothing but the ground plan. With the placing near the church we can guess that the vicar and other staff of the church were to have their dwelings here, but the complex is so big that other functions might be suggested: The wing towards East (closest to the ramparts) may have been intended as stables for the horses of the calvalry or the higher officers of the garrison, and coach-houses.
The reconstruction is pure speculation made to fill out an empty part of the Citadel and arranged so that the church is shown with some surroundings.
An architectural point is - as by the "royal building" and the stores - the typical contrast between the tall and low buildings.