Europe was once filled with small states.  Over time they consolidated to form large kingdoms - then nations.  Luxembourg has been part of much larger royal possessions, but it has remained independent.  How has the Duchy of Luxembourg survived?  Luck, royal marriages, and fortifications.  The original defenses date to medieval times, but over time Luxembourg became so heavily fortified, it was known as the Gibraltar of the North.  Luxembourg was easy to defend.  It is positioned on high ground with cliffs and the River Alzette and the River Petrusse protecting three sides of the town.  Vauban besieged and captured the city in the 1680s then proceeded to strength the defenses.  The French, after spending large sums on the place, had to return Luxembourg to the Spanish in 1697.  Then 1713, Luxembourg was given to the Austrians, who also improved the defenses.  In 1795, Luxembourg surrendered to the revolutionary French, but only because supplies were running low.  After 1815, Prussians garrisoned the city, which was owned by the Dutch.  War between Prussia and France was prevented in 1867 by a treaty making Luxembourg neutral.  According to the Treaty of London, most of the defenses were demolished.  Although only around 10% of the city's fortifications remain, they provide an interesting look at was once one of the greatest fortresses anywhere.

    Luxembourg has been inhabited since Roman times, and in the Middle Ages it became an economic and religious center.  In 963Count Siegfried acquired the Bock promontory on easily defended high ground.  A castle was built on a projection of land indicated by the red dot on the drawing.  By the late Middle Ages, roughly 5,000 people lived in the town of Luxembourg.  

From Beck Bastion

     Built atop rock cliffs, Beck Bastion looks south across a tributary of the Alzette.  The ruins of Fort Bourbon, designed by Vauban, can be seen across the valley.  The defenses on the less easily defended west side of town, an interesting and complex system, has been largely developed over, and there is little to see now.

Fort Bourbon From Bastion Bock

Looking East.  Note casemates in rock below walls.

Looking West

World War I Memorial in Bock Bastion


Bock Castle - 13th Century

    In the 10th century, Bock Castle was simply a wooden tower surrounded by a palisade.  Later additions included a chapel, a tower, and a wooden bridge connecting the castle to the growing town.  In the late tenth century, city walls were built to protect the town, and in the 12th century the walls were improved.  By the thirteenth century, the castle was much improved, but in the late fourteenth century, the castle was no longer used as a residence.  In the fifteenth century the castle was partially destroyed by the Burgundians.  

Bock Casemates

    Walking along the walls - east from Beck Bastion, we can see the walls angle north on the left side of the photo.  The brick bridge in the center of the panorama crosses to the site of Bock Castle on a rocky ridge projecting forward to the northeast.  We will continue walking in that direction.

Bock Casemates

Walking further along we see the bend in the Alzette, an area known as the Rham Plateau, which was also protected by fortifications.  We will get a better view of those defenses next from the Bock Casemates.

From Bock Casemates

     From Bock Casemates you can see the old medieval wall, later modified, crossing the Alzette then pivoting and climbing uphill to Tower Jacob.  In the 19th century a military hospital was built in the bend of the river next to an abbey.

Tower Jacob

Bock Casemates

     The first casemates were dug in 1644 while Spain controlled the city.  After the capture by Vauban, the underground works were continued, and after takeover by the Austrians, construction continued further.  A fort in three sections was on top of the casemates, no longer in existence, making the ridge a formidable artillery platform with 50 guns dominating the valley below.

     The tunnels extended to such an extent that when Luxembourg was neutralized in 1867, it was impossible to destroy the tunnels without endangering the city's buildings above.  In the Second World War, the casemates were used as shelters for civilians.

     Despite the strength of the Bock position, Vauban smashed the fort during his 1684 siege with artillery on the heights across the river.  Given the opportunity to enhance Luxembourg's defenses after the war, he added works on these heights and also on the Rham Plateau.



     The drawing and the map show the eastern defenses - Vauban's new works and later improvements by the Austrians and Prussians.  Fort Obergrunewald and Fort Thungen have been restored.  To visit them, first we cross the Alzette and walk past a flour storehouse and a Vauban tower.

Grunewald Gate and Flour Storehouse

     In the panorama above, the three part tiered building at center was designed to store the garrison's supply of flour, built originally of wood in 1733 by the Austrians in Hiel. valley.  The flour was preserved barrels to protect it from insects and mice.  In 1771 the building was renovated with masonry.  The appearance of building here today resembles the time period between 1815 and 1866.

     On the left of the panorama, the tall building is the Grunewald Gate.
 This gate was originally built in 1685 with a ditch and loopholes.  An infantry defense tower, on either side were walls with loopholes fronted by a ditch.  The wall connected the city's inner defenses with those on the high ground across the Alzette.  Gated towers like this were designed to strengthen the connecting wall.  The walls on either side of the tower have since been demolished, and the present tower approximates its 1836 appearance as modified by Prussian engineers.

     Next we walk up a path to Fort Obergrunewald.

Fort Obergrünewald - Rear Entrance

     We have walked up the paved path at left from the Grunewald Gate and have entered the rear of Fort Obergrunewald.  The fort 's corner can be seen in the photo at right, which suggests that the wall is not restored to its full height.  Within this corner was a powder magazine, built in 1860 but no longer extant.  After angling back, the wall continues to the main fort.  At this junction, another wall descended into the valley to the Grunewald Gate.

     Where we are standing was a
redoubt - a bomb proof vaulted tower which served as a refuge for soldiers when under attack or bombardment.  The redoubt also allowed fire from its casemates to cover the walls on either side.

     Next we continue along the path uphill and into the fort.

Vauban left the rear unfortified so that if captured, the fort could be dominated by fire from the city itself.  The Austrians felt differently and built a wall to the rear of the fort.

Postern With Guardhouse Ruins at Left

Continuing along the path we come upon the postern - an entrance into the main part of the fort, which is a hornwork.  

This is looking along the length of the underground passage.  Barely visible on the far sides of the photo are stairways up to the top of the fort.  You can see the passageway level off; this is the caponier.  At the end, stairs climb to the demi-lune, and the man that you see is facing an opening into the ditch.
At far left is where we entered.  This is looking left up the stair to the top of the fort.
This is the end of the passageway.  At left is a passageway that once led to a small powder magazine which could hold about a day's worth of powder.  The stairway climbs up to the demi-lune.




These are views inside the caponier, which includes firing ports so that the infantry fire can dominate the ditch.

Next, we climb the steps to the demi-lune.


From the demi-lune you can better understand the caponier.  It is a vaulted, bombproof casemate protected from direct infantry attack by ditches on either side and protected from direct artillery fire by the demi-lune to its front.

Here is a panorama from the same location.  The fort faces uphill, but Vauban thought this preferable to leaving the heights undefended.  The long stairs at right did not exist, rather this was a gentle slope leading up to another fort.

Fort Obergrunewald - Ditch

We have walked down the stairs within the demi-lune and have walked out of the caponier and into the ditch.  Next we will walk up the path toward and beyond the traverse to get a view of the front of the fort.

We are now on the covered way, an area defended by the infantry.  The long stairs at right did not exist at the time, so the infantry had a smooth field of fire from here.  The covered way was the front line of defense.  The traverse at far right allowed for sorties or patrols to be launched on either side of it.  If the enemy captured the section of the covered way where we are standing, defending infantry could fire on them from behind the traverses on the left and center of the panorama.  Next we will walk around the traverse in the center.

Fort Obergrunewald - Place of Arms

The covered way is about six meters wide and two meters below the crest of the glacis, the open field of fire, in order to provide protection against enemy fire and observation.  The soldiers were positioned in ranks, and to be able to fire, they had to stand on the slightly raised ground in order to raise themselves up enough to fire.

Atop the modern steps you get a good elevated view of Fort Obergrunewald.  On the far right of the panorama is another fort, Fort Thungen, named after the Austrian commander of Luxembourg, marked as "redoubt" - originally Vauban's Redoubt du Parc.  We will continue to the front of it.

Redoubt du Parc

Redoubte du Parc was designed and built by Vauban in 1688.  That is what we see here - but with a modern art museum atop it.

1726, Austrian Major General Simon Beauffe was ordered to Luxembourg to direct the extension of the fortifications.  In 1730 he wrote that he could quickly perfect Vauban's redoubt, and he developed plans for a third defensive line made of seven outworks.   These bombproof outworks were not in a strict defensive line but rather were several hundred meters apart and designed to mutually support each other.  These types of works marked the end of the bastion system that had dominated fortification since the 1500s.

Fort Thungen

This is the side view.  The older section is at right, and it now has a modern art museum atop it.  At left is the Prussian modification.

The Prussians modified Fort Thungen in the 1830s.  Note decorative acorns atop the towers.

Initially, the entrance to the Austrian redoubt was very narrow and was located almost at entrance of the system of mines.  During upgrades of 1836/37 the Prussians raised the level of the interior of the redoubt and partially filled the ditch.  A stone foundation was built in order to hold up the larger bridge piers.  

According to the plans of 1821, the drawbridge had to be designed so it could be be raised and lowered by hand.  The deck of the drawbridge, weighing about 600 kg, can be moved up or down by two people thanks to a system of thirteen counterweights of 21 kg each on the chains on each side. When the bridge deck is lifted, the counterweights support human effort, while on the way down, they serve as brakes.

Caponier Connecting the New with the Old

Copyright 2012 by John Hamill

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