RTL Today contributor Thomas Tutton explains how Luxembourg became such a strategically important military fortress in early modern history.

From 1482 to 1795, the Duchy of Luxembourg, with only short interruptions, was the property of the Habsburg family, who weren’t always the brightest bunch.

This wasn’t great for Luxembourg as it embroiled the territory in an almost endless series of conflicts between the Habsburgs and the French.

So why did Luxembourg become such a constant theatre of war?

Origins of the Franco-Habsburg Rivalry

The Habsburg family, through wise marriages and careful accumulation of lands, had come to dominate most of present-day Austria, Czechia and Hungary by the mid-15th century.

This had made them extremely influential in the Holy Roman Empire, and once Frederick III was crowned Holy Roman Emperor in 1452, the family would hold onto the title until 1806.

On the other hand, the Valois family had finally wrested control over France away from the British by the end of the Hundred Years War in 1453.

This left the Kingdom of France ready to expand on the continent.


The Kingdom of France was encircled by Habsburg lands. / © Public domain

However, as we have previously explored, by the time Charles V was 19 in 1519, he had inherited the Habsburg crown lands in the Holy Roman Empire, Spain, the Netherlands (including Luxembourg), and parts of Burgundy.

The Kingdom of France was encircled on every side by Habsburg lands, and this could only lead to war, which would last on and off for about 250 years.

The First Franco-Habsburg Wars: Luxembourg Occupied

The primary battleground between the Valois and the Habsburgs in the early 16th century was Italy: the Italian Wars were a series of conflicts over the future of the Italian peninsula that lasted from 1494 to 1559.

The nominal issue was over ownership of the Duchy of Milan, but this was in reality both a geopolitical conflict between rival dynasties and a personal vendetta.

Francis I of France (1515-1547) really hated Charles V, to whom he had lost the election for King of Germany in 1520.

In 1526, Francis had been captured by Charles V’s soldiers and imprisoned in Madrid; in 1536, he established an alliance with the Muslim Ottoman Emperor Suleiman the Magnificent, which was highly controversial at the time for a Christian power.


King Francis I of France was an admirer of the House of Luxembourg and the rival of Charles V. / © Public domain

This period saw conflict reach Luxembourg, which was in a vulnerable position as the southern end of the Habsburg Netherlands.

Francis was apparently a big admirer of the old House of Luxembourg and wanted the title of Duke of Luxembourg for himself, so in 1542 he sent French troops under his son to capture the fortress.

And the events of 1542-44 show that Luxembourg was initially quite vulnerable as a military fortification.

Setting up their artillery on the heights of what is now Kirchberg, the French managed to bombard the town into submission, but they were chased out after two weeks.

They returned in 1543, but the fortress was finally recaptured by Charles V’s forces after a long siege in 1544.

And with events in Italy proving more important, Francis abandoned his efforts to take Luxembourg.

But the French would be back.

Civil Wars, and Luxembourg Fortified

Charles V abdicated in 1556, leaving the Netherlands and Luxembourg to his son, the Spanish King Philip II.

The rivalry between the Habsburgs and the French subsided for a time, as everyone decided to take a break from foreign wars and focus on religious civil wars.

Martin Luther had blown Christianity apart with his Ninety-five Theses in 1517, and the consequences would be keenly felt for the next few centuries.

Between 1562 and 1598, France collapsed into a series of civil wars known as the French Wars of Religion, including the St Bartholomew’s Day massacre of Protestants in 1572.


Peter Ernst von Mansfeld was Governor of Luxembourg from 1545-1604. / © Public domain

Meanwhile, the Dutch Revolt broke out against Habsburg rule in the Spanish Netherlands, beginning an Eighty Years War of independence.

During this period, Luxembourg was heavily fortified by its Spanish Habsburg rulers under Governor Peter Ernest von Mansfeld.

The fortress at Luxembourg was reinforced, while a whole network of fortified towns and castles was set up around the Duchy, including Arlon and Virton (now in Belgium) as well as Montmédy and Thionville (now in France).

Wars, Wars, Wars

Under Governor von Mansfeld, Catholic Luxembourg did not join the mostly Protestant Dutch Revolt; instead, it became one of the centres of resistance to the Dutch.

With France recovering under the new Bourbon King Henry IV, it decided to pursue a policy of weakening the Habsburgs wherever it could without openly declaring war.

The obvious way to do this was to support the Dutch rebels, and Luxembourg thus came under attack from all sides.

The Spanish Habsburg rulers poured in mercenaries to fight against the Dutch, and the countryside was ravaged by armed men who did not care at all about the local population.


Scenes of plunder, as shown in this painting of the devastation of Wommelgem, were common in the Duchy of Luxembourg during the Dutch Revolt (1568-1648). / © Public domain

The fortress of Luxembourg itself came under siege briefly in 1593 and 1597, while Franco-Dutch forces took Montmédy, Virton and Echternach.

A brief truce under the happy reign of Isabella Clara Eugenia and Albert, Sovereigns of the Netherlands, ended by 1621, and the Dutch Revolt now became part of the wider Thirty Years War (1618-1648) which engulfed the whole of Europe.

Luxembourg once again faced constant warfare between Spanish mercenaries, Dutch rebels and French troops, with its villages being pillaged and an estimated 2/3 of the population dying of famine and plague.

On top of this, the French, now under Louis XIII and his minister Richelieu, now decided to make the conflict with the Habsburgs official again, beginning the Franco-Spanish War of 1635-59.

The Treaty of Westphalia of 1648 brought the Thirty Years War and the Dutch Revolt to an end, but the Franco-Spanish conflict continued to rage to the detriment of the Luxembourgish population until the 1659 Treaty of the Pyrenees produced a feeble peace.

At this point, the Duchy of Luxembourg suffered its first partition with Montmédy and Thionville falling to the French.

But the Franco-Habsburg conflict was far from over, and as we will discover next week, the late 17th century would see the Sun King Louis XIV take over Luxembourg.