Hadrian’s Military Strategy and Defensive Policies (117–138 CE)

Unlike his predecessor Trajan, who pursued an expansionist policy, Emperor Hadrian (r. 117–138 CE) took a more defensive approach to Rome’s frontiers. He renounced most of Trajan’s eastern conquests, making no attempt to reclaim Parthian territories briefly occupied by Roman forces. However, he retained the province of Dacia, recognizing its strategic and economic importance.

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Hadrian’s Defensive Strategy and Military Reforms

Hadrian’s "peace through strength" policy focused on fortifying Rome’s borders (limites) rather than expanding them.

1. Hadrian’s Wall: Defending Britain’s Northern Frontier

• The most famous of Hadrian’s defensive projects was Hadrian’s Wall in Britain, constructed to mark the empire’s northernmost boundary.
• Built around 122 CE, it stretched 73 miles (117 km) across northern England, featuring:
  • Stone walls and ditches to prevent incursions.
  • Forts and milecastles housing Roman garrisons.
  • Watchtowers and roads for rapid communication.

2. Strengthening the Danube and Rhine Frontiers

• In continental Europe, Hadrian reinforced the Danube and Rhine borders, constructing:
  • Fortified camps and wooden palisades to control movement.
  • Outposts and watchtowers for early warning and security.
  • Improved communication networks to facilitate troop movements.

3. Military Discipline and Readiness

• Hadrian was deeply involved in military affairs, frequently touring the provinces to inspect Rome’s legions.
• He implemented:
  • Rigorous drill routines to maintain discipline.
  • Strategic deployments to respond quickly to threats.
  • Reforms ensuring better training, supply chains, and troop welfare.

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Hadrian’s Military Image and Propaganda

Despite his defensive policies, Hadrian projected an image of military strength and preparedness:

• His imperial coinage often depicted:
  • Victorious soldiers to symbolize Rome’s military power.
  • Fortified cities and provinces, reinforcing his commitment to defense.
  • Images of Hadrian in military attire, maintaining his connection with the army.

Hadrian’s approach balanced military pragmatism with imperial propaganda, ensuring that Rome remained secure without overextending itself.

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The Legacy of Hadrian’s Defensive Policies

• His fortifications and strategic reforms helped stabilize Rome’s borders for much of the 2nd century CE.
• His policy of consolidation rather than expansion marked a shift in imperial military doctrine, influencing later emperors.
• Hadrian’s Wall and other fortifications became enduring symbols of Roman engineering and military organization.

By prioritizing defense and stability over conquest, Hadrian preserved the strength of the Roman Empire, ensuring that it remained resilient in an era of growing external threats.

Germanic invasions in the late third century lead to the abandonment of the so-called "Upper Raetian Limes" in favor of a Roman defense line along the rivers Rhine, Iller and Danube (Donau-Iller-Rhine-Limes) with watch towers in sight contact and heavily fortified castra at important passes (e.g., Castrum Rauracense instead of the previously unwalled Augusta Raurica near to Basel) and in the hinterland of the frontier (e.g., Vindonissa in today's Switzerland).

The two centuries of order and prosperity brought by the Pax Romana to Switzerland had ended, as elsewhere in the Empire, with the Crisis of the Third Century.

In 260, when the Gallic Empire had briefly seceded from Rome, the emperor Gallienus had withdrawn the legions from the Rhine to fight the usurper Ingenuus, allowing the warlike Alemanni to enter the Swiss plateau.

Here, cities, villages and most villae have been raided or sacked by marauding bands.

The numerous caches of coins recovered from the period between 250 and 280 attest to the severity of the crisis.

Only the Valais, shielded by mountains, has escaped these predations.

Owing to the constant threat of invasion, the cities in Gaul now construct or reinforce their defensive walls.

The widespread civil unrest during the Crisis of the Third Century has made it no longer safe for merchants to travel as they once had, and the financial crisis that struck has made exchange very difficult.

This has produced profound changes that, in many ways, foreshadow the character of the coming Middle Ages.

Large landowners, no longer able to successfully export their crops over long distances, have begun producing food for subsistence and local barter.

Rather than import manufactured goods, they have begun to manufacture many goods locally, often on their own estates, thus beginning the self-sufficient "house economy" that is to become commonplace in later centuries, reaching its final form in Manorialism.

The common free people of the cities, meanwhile, have begun to move out to the countryside in search of food and protection.

Made desperate by economic necessity, many of these former city dwellers, as well as many small farmers, have been forced to give up basic rights in order to receive protection from large land holders.

In doing so, they have become a half-free class of citizen known as coloni.

They are tied to the land, and in later Imperial law their status will be made hereditary.

This provides an early model for serfdom, which will form the basis of medieval feudal society.

Even the cities themselves have begun to change in character.

The large, open cities of antiquity are slowly giving way to the smaller, walled cities that will be common in the Middle Ages.

These changes are not restricted to the third century, but will take place slowly over long periods of time, punctuated with many temporary reversals.

However, in spite of extensive reforms by later Emperors, the Roman trade network will never be able to fully recover.

The decrease in commerce between the provinces have put them on a path towards increased insularity.

Large landowners, who have become more self-sufficient, have become less mindful of Rome’s central authority and are downright hostile towards its tax collectors.

The measure of wealth at this time begins to have less to do with wielding urban civil authority and more to do with controlling large agricultural estates.

The common people have lost economic and political power to the nobility, and the middle classes have waned.

The Crisis of the Third Century thus marks the beginning of a long evolutionary process that is to transform the ancient world into the medieval one.

The Tauredunum event, a mountain landslide into the Rhone river, destroys a fort and two villages and creates a tsunami in Lake Geneva.

The wave that reaches Lausanne is thirteen meters high, and …

...eight meters high by the time it hits Geneva.

Describing the event, Marius Aventicensis writes that the tsunami "devastated very old villages with their men and cattle, it even destroyed many sacred places", and swept away "the bridge in Geneva, windmills and men". (”Des chercheurs reconstituent le tsunami du lac Léman de l’an 563", Le Monde, October 28, 2012).

There is evidence of four previous mudslides, suggesting that tsunamis may be a recurrent phenomenon on Lake Geneva.

Magyars invade Germany and Italy in 921.

Although a sizable force is routed near Bleiburg in the Bavarian March of Carinthia by Eberhard and the Count of Meran and another group is routed by Liutfried, count of Elsass (Alsace), the Magyars repeatedly raid Germany.

The bridge over the River Inn, which gives Innsbruck its name, has made the eastern Alpine city an important point on the trade routes to Germany from Italy and Switzerland by the twelfth century.

Originally belonging to the counts of Andech, Innsbruck passes to the Habsburgs in 1363 when the Tyrol becomes a Habsburg possession.

The Invention of the Canal Lock and the Expansion of European Waterways (Before 1500)

The invention and widespread use of the canal lock before 1500 revolutionized water transportation in Europe, enabling the construction of larger, more complex canal networks that facilitated trade, agriculture, and urban expansion.

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The Development of Canal Locks

• Early canals were simple structures that connected rivers and lakes, but they faced problems with differing water levels.
• The first primitive locks, known as flash locks, allowed boats to pass but required temporary flooding, which was inefficient and often dangerous.
• The true innovation came with the pound lock, which consisted of a chamber with gates at both ends, allowing for controlled raising and lowering of water levels.

Key Early Innovations

• China (10th century) – The first known pound lock was built in 984 CE by engineer Qiao Weiyue during the Song Dynasty.
• Italy (15th century) – Leonardo da Vinci designed improved mitered gates, which became the standard for European canal locks.
• Netherlands and Flanders (1400s) – Early locks were used in lowland areas to control flooding and improve navigation.

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Impact on European Canal Construction

With the adoption of the canal lock, European nations began constructing larger, more efficient canal systems to support commerce, agriculture, and urban development.

Notable Pre-1500 Canal Projects

• The Naviglio Grande (Italy, 12th–15th century) – One of the first major navigable canals, improved by Leonardo da Vinci’s lock designs.
• The Stecknitz Canal (Germany, completed 1398) – One of Europe’s first summit-level canals, connecting the Elbe and Trave Rivers.
• Flemish and Dutch Canals – Used for drainage, transport, and flood control, supporting the growth of mercantile cities.

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Effects of the Canal Lock on European Development

1. Increased Trade and Commerce

   • Goods could be transported more efficiently, reducing costs and travel time.
   • Cities connected by canals became major trade centers (e.g., Venice, Bruges, Amsterdam).

2. Urban and Industrial Growth

   • Canals supplied water to growing cities and supported early manufacturing industries.
   • Locks allowed for the development of large inland ports.

3. Agricultural Expansion

   • Improved irrigation systems and water management.
   • Enabled land reclamation in low-lying regions like the Netherlands.

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Legacy: The Rise of Europe’s Great Canals

By 1500, the use of canal locks had spread throughout Europe, paving the way for the major canal-building era of the 16th–19th centuries, including:

• The Canal du Midi (France, 1681) – One of the first modern long-distance canals.
• The Grand Canal (England, 18th century) – Linked industrial regions to ports.
• Dutch and German canal networks, expanding inland trade.

The invention of the canal lock was a major engineering breakthrough, transforming European transportation, commerce, and urban development, ultimately playing a key role in the economic expansion of early modern Europe.

 

At least thirty-four people are killed in Switzerland, when the melting of the Giétro Glacier releases the natural dam of Lac de Mauvoisin, sending the waters of the lake and the Dranse River into the valley of Bagnes on June 18, 1818.

After an increase of the glacier during the "Year Without a Summer", an ice cone had started to form in 1816 in the valley.

It was created by the accumulation of the falling seracs of the terminus.

A lake was formed but it emptied on May 27, 1817, without causing any fatalities.

In April 1818 the lake measured about two kilometers in length

On May 10, 1818, the engineer Ignaz Venetz had been called by the canton.

To stop the rapid rise of waters, he decided to drill a hole through the ice. The work began one day later.

A tunnel was drilled from the two sides, about twenty meters above the level of the lake.

An avalanche of ice occurred on May 18 but without any casualties.

A secondary tunnel was then drilled for safety reasons.

A week later the level of the lake reached 10 meters below the tunnel.[

On May 27 an enormous piece of ice detached itself from the cone in the lake and floated to the surface while making terrible noise; everybody escaped.

They went back to work two days later.

The none hundred and ninety-eight meter-long hole was completed on June 4.

Other large pieces of ice detached from the cone and floated back.

The waters finally reached the level of the hole on June, 13, at 22:00.

They continued to rise until June 14, when the level of the lake began to fall because of the erosion of the hole by the waterfall.

Some water also ran out from the base of the cone.

Only two men stayed in place; Venetz warned the inhabitants of the valley of the danger

On the morning of June 16, terrible noises and violent detonations were heard.

The cone began to crack.

A group of British tourists and a sketcher from Lausanne visited the place with Venetz.

In the afternoon, Venetz and the workers escaped to the heights of Fionnay.

Finally, at 16:30, the dam broke and eighteen million cubic meters of water invaded the valley.

Half an hour later the lake was empty.

The flood reached the village of Bagnes ten minutes later; the alert was given to Martigny before 18:00, but too late.

The wave invaded Martigny-Bourg a few minutes later.

The rise of the waters was observed along the Rhone, at 19:00 in Saint-Maurice and at 23:00 on Lake Geneva.