Article and pictures by David Flintham, all rights reserved.
Boulogne-sur-Mer's often overlooked old (or upper) town, is quite charming and is well worth the climb from the more modern Boulogne (or lower town), and its now underused port.
The shape of Boulogne's defences betrays its Roman origins. As one of the closet points to England, it was strategically important to the 43 AD Claudian invasion. In the 2nd Century, a military camp was established overlooking the estuary of the River Liane and was the base of the Classis Britannica (the Channel fleet). This castrum followed the standard Roman pattern and was laid out within a large rectangular wall with four gates, one per side. In addition, there were four internal quadrangular towers.
The general layout of the Roman settlement of Bononia remains largely unchanged to the present day, as successive fortifications followed the original Roman lines. At the beginning of the 4th Century, new fortifications were built, including higher and thicker walls and a number of semi-circular towers, still visible in the basement of the castle. It was within these walls that feudal Boulogne developed.
The thirteenth century was a time of rebellion in this corner of what was to become France. Renaud de Dammartin, count of Boulogne, allied himself to the Holy Roman Emperor, the count of Flanders and the King of England, but was beaten in 1214 by the King of France who stripped him of his title and possessions. Philippe Auguste gave the earldom to his bastard son, Philippe Hurepel ("the prickly").
Following the death of his half-brother King Louis VIII in 1226, Philippe Hurepel, now count of Boulogne, joined the rebellion against Blanche de Castille, mother and regent of the infant Louis IX.
It was during this opposition to the royal family that Hurepel undertook to improve the defences of his territory. Along with the castles of Calais and Hardelot, he built Boulogne château (completed in 1231) at the eastern corner of the town's fortifications, which he also improved.
The fortifications comprise a 325 by 410 metre quadrilateral (a total length of 1,500 metres), with four gates and 17 semi-circular towers, with a larger tower at the north, south and west corners. The 13th century walls would have been crenellated and the towers would have been at least a floor higher than the walls and topped with pepperpot-shapped roofs . The four gates (the Calais Gate was rebuilt in the 17th century and became known as the Porte Neuve) each comprised an entrance defended by two semi-circular towers pierced with arrow slits. The best-preserved gate is the Degrés Gate which still retains traces of its defence mechanisms including portcullis grooves.
The château was the most important element of Boulogne's defences. It reinforced the eastern corner of the fortifications that were considered to be the most vulnerable and was joined to them by a bridge across its moat. In terms of shape, it is a slightly irregular 9-sided polygon with each corner flanked by a round tower. Built on a sunken level, the main body of the building backs onto the edge of the curtain wall and opens onto a central courtyard. Two towers protect the west-facing main entrance, whilst there is a smaller entrance to the southeast.
The layout and absence of a keep exemplified the new styles of fortified architecture built during the reign of Philippe Auguste. And the relationship between the château and the walls foreshadowed Vauban's citadels.
The earldom of Boulogne became the property of Burgundy and it wasn't until 1478 that Louis XI finally united it with the French crown. On the northern extreme of the kingdom, Boulogne and its surrounds formed a salient which was a feature of 16th and early 17th century France. With its base on the River Somme, the salient stretched along the northwest coast towards Calais and as far east as Thèrouanne. Defended by Montreuil, it sat on the eastern flank of the Spanish invasion route from the Habsburg Netherlands, and being just twenty miles south of the English possession of Calais and within sight of the Kent coast the "Boulogne Salient" was strategically important  and, at the same time, vulnerable.
As a result, the English coveted and besieged it twice. The first siege of 1492 led by Henry VII (Tudor) took the lightly defended lower town. But 50 years later, the English, as an ally of the Holy Roman Emperor in his war against the French, returned, under his son, Henry VIII.
The siege commenced on 19 July 1544. Under the military command of Jacques de Coucy and the civil command of its mayor, Antoine Eurvin, 1,800 French soldiers, 500 Italian mercenaries and the town's militia garrisoned Boulogne. Henry VIII personally commanded an army of 30,000 and powerful siege artillery. He hired the Italian engineer, Girolamo Pennacchi to oversee the construction of the siege-works but within a few days he was killed by a cannon ball. After a creditable five-week defence, the governor (against the advice of the leading citizens who no doubt scented what was to come) surrendered Boulogne on 13 September. The garrison, and some of the townspeople were permitted to march off for Etaples and Abbeville, but pillagers harried them as they went. As the citizens feared, the town was sacked and the miraculous statue of the Virgin, left in Boulogne by the Merovingian King Dagobert in 636, was carried off to England .
Whilst this was to be the last occasion when English forces were to dispute a fortress with a Continental power during the Early Modern period, it also enabled Henry to see for himself the features of fortifications then being developed on the Continent and may have influenced the design of the second phase of Henry's coastal defence schemes .
Shortly after the surrender of Boulogne, the Treaty of Crépy-en-Valois ended the fighting and as a result, Henry brought most of his troops back to England. Yet within weeks of capturing the town, it was almost lost again as the result of a surprise attack by the French: indeed it was probably only the fact that the French soldiers' attention became focused on plunder prevented its re-capture. Shaken by what was so nearly a defeat, the English were prompted to make efforts to protect their new territory.
To this end, John Rogers'was appointed to oversee the construction of the defences, not only at Boulogne itself, but also at Ambleteuse and Cap Gris-Nez. Boulogne's existing defences were improved, including the vaulting of parts of the château to take artillery platforms. But to contemporaries, it was the fortifications built outside the upper town itself that would have been the most striking.
An outwork was built to the northeast to defend the vulnerable upper town, whilst to the southeast, ramparts some 2,430m in length were constructed around the lower town. This included bastions to the north and south and at its southeastern corner, overlooking the River Liane and Boulogne's harbour, a bastioned'citadel-like feature. At the mouth of the river was the Tour de l'Ordre, a lighthouse dating from Roman times. It was fortified by the English (to whom it was known as the "Old Man"), and the fortifications took the form of an angular work, some 490m across with three arrow-headed bastions. This was later linked to the lower town by a rampart. These were amongst the first bastioned works ever built by the English.
A 17 th Century map of Boulogne (see right) clearly shows the remains of these and the later Henry IV defences, including the fortified Tour de l'Ordre (at the top left of the map) the north-eastern face of the lower town defences (connected to the upper town at the Porte des Dunes), the northward extension towards the Tour de l'Ordre, and the outwork at the 13th Century château, which was built by the English and later modified.
L. R. Shelby in his John Rogers: Tudor Military Engineer, suggested that, whilst wining the "race" to the river mouth (and fortifying the Tour de l'Ordre), it was an oversight of the English garrison not to fortify the heights on the south bank of the Liane . This enabled the French to construct rival fortifications, including the pentagonal Fort d'Outreau, a citadel some 245m metres across with five bastions, located some 1,330m to the south of the English lower town fortifications. Further south (some 2,900m from the lower town), there was a substantial fortified camp, with a bastion at each corner, a flank bastion on each flank, with a total rampart length of an estimated 2,280m. But despite having complete control of the south bank, due to the topography of the area the French were never quite able to prevent English shipping from entering and leaving the harbour.
Thus the French blockade was never complete and ultimately, it took tortuous negotiations and a payment of 400,000 gold écus before the town was finally returned to French rule in 1550 . To mark the occasion, Henry II gave the town a silver statue of the virgin to replace the one stolen by the English.
Eight years later, Calais was also back in French hands, finally removing the English threat to the Salient and enabling French operations against the Spanish Netherlands to proceed unmolested.
The growth of Lutheranism in the Spanish Netherlands spread into Artois and given the close trading links with England, religious and resulting political unrest was most serious in the coastal areas, Boulogne included, where, in 1567, citizens rose up against its priests. Catholicism was not re-established until the following year. France's Wars of Religion did not end until 1598. Prompted by Spanish successes in seizing French fortresses, Henry IV of Navarre, through his minister, Sully, undertook a programme of improvement to the fortresses along the northern frontier . In Boulogne, these improvements took the form of levelling the towers and curtain walls and adding wide ramparts to take artillery. Turning to the upper town, five of its nine towers were incorporated into thick stonework designed to protect the eastern side from artillery. In addition, it is likely that there were some external earthworks (the 17th Century map of Boulogne suggests the location of post-1540s fortifications at both the Tour de l'Ordre, and external to the châteaux). Whilst it cannot be said for certain, it is likely that these improvements were overseen by Jean Errard'(who is known as the "father of French fortification") .
As the size of armies increased, the Boulogne Salient proved to be too narrow and constrictive for the formation of armies to engage the Spanish during the final decade of the Thirty Years War. As a result, from 1638 the French set about expanding the salient, a task that occupied them until the civil wars of the Fronde .
At the end of the 17 th century, Vauban'envisaged modernising the fortifications, describing the existing fortifications thus: The upper town takes the shape of an elongated square, well furnished and fortified with ancient towers. There are large towers of boulevards of very thick stonework found at the corners of the square and in the vicinity of the gates...The old castle sits in one of the corners of the square, the abode and fortress of the former counts of Boulogne... 
But because of the cost, Louis XIV'refused, preferring to use the money to improve the defences of Calais . Anyway, with France advancing her borders, Boulogne was no longer strategically important. In 1689, therefore, it was decided that the defences should be demolished. Fortunately, the local population resisted and it is thanks to them that the defences remain to this day. In 1785, the Gayette Tower, at the western corner of the fortifications, was the spot where balloonist Pilatre de Rosier took off in his unsuccessful attempt to cross the Channel .
After being semi-abandoned, the castle was fitted out as a barracks in the 18th century and, as a result, was the subject of further modifications - the main body of the building was heightened, pierced with large windows and covered with a mansard roof. From the end of the Second World War until 1974, the castle housed a prison.
Whilst outside the direct scope of this article, Boulogne's military heritage went right up to the 1940s. In 1804, Boulogne was the base for Napoleon's army (later to become the Grande Armée), which he was assembling to invade Britain, an event commemorated by the Colonne de la grande Armée that overlooks Boulogne. In 1840, Louis-Napoleon (the future Emperor Napoleon III) attempted an abortive coup from Boulogne.
During the Second World War, Boulogne witnessed further fighting, and the old town was the scene of the "last stand" of General Lanquetot's 21st Infantry Division in May 1940 who only surrendered from their final position around the Calais gate when the Germans threatened to destroy the town and cathedral . But most significantly from a fortress perspective was the location of new defences (including around the French Fort de la Crèche and a German battery overlooking the port, both of which survive to this day) as part of Hitler's Atlantic Wall.
Debussche, Frédéric, Cities and Countries of Art and History - Boulogne-sur-Mer
Duffy, Christopher, Siege Warfare - The Fortress in the Early Modern Word, 1494-1660, (London, 1979), pp. 43-45.
Holmes, Richard, Fatal Avenue, (London, 2008), p. 128
Harrington, Peter, The Castles of Henry VIII, (Oxford, 2007), p. 45.
I am indebted to Dominic Goode for his summary of the description of the English fortifications from Shelby, L. R., John Rogers: Tudor Military Engineer, (Oxford, 1967).
Duffy, pp. 47-48 and Holmes, p. 128.
Duffy, pp. 112-115.
Lepage, Jean-Denis, Vauban and the French Military Under Louis XIV, (Jefferson, 2009), p. 66.
Duffy, pp. 130-131.
Vauban, Sébastien Le Preste de, Archives du Génie, (1675).
Lepage, p. 144.
Holmes, p. 129.
Holmes, p. 274.
Article and pictures by David Flintham, all rights reserved.