Traditionally, WWI and WWII are considered two different historical events, with very little in common. But in recent years, a new historical concept has emerged which considers these two wars the beginning and the end of a long period of conflict: a single, 30-year-long European civil war. 

It is a very complex concept, and not all historians adhere to it. 

Historians who are sceptic about the European civil war point out how the two World Wars have very different characteristics in terms of unfolding and evolution; how WWI can only marginally be considered a ‘world’ war, while the second had battlefields scattered throughout the globe; and how WWII can actually be considered a war between different ‘civilisations’. 

Historians who adhere to the European civil war concept point out that, although in different ways, WWI was as much a ‘world’ war as the second and actually kicked off the concept of ‘global war’. But above all, they intend to be ‘civil’, a war not just fought inside the same civilisation, as the term is normally understood. The world wars of the 1900s are ‘civil’ because they shattered the classical patterns of war, left the battlefield, and entered the civic space.

Jus Publicum Europaeum

Traditionally, war and civil life had lived in parallel worlds. Wars happened on the front and involved the army, soldiers, weapons for periods of times that were relatively short. Civil life was elsewhere and mostly flew on as always, despite the war. 

The Napoleonic Wars in Europe were the first break of this system. These wars involved a great number of nations and started to absorb part of civil life because of the great number of resources it required. It was a terrible experience in the continent’s history, and when it was over, all chancellorships in Europe tried to find a way to prevent any such occurrence again. Thus the Concert of Europe came to be. All European countries, who recognised each other as part of the same civilisation living by roughly the same laws, agreed on a system that allowed to settle quarrels through diplomacy rather than through conflict. 

Throughout the long, peaceful 1800s, conflicts still broke out in Europe, but they were usually regional affairs. When diplomacy could not solve a problem, wars were still allowed if they involved small portions of the continent and addressed very specific questions, which had a chance to resolve once the war was over without involving too many resources and efforts. 
The Crimean War was such an example. 
This balance of powers came to be known as the Jus Publicum Europaeum.

The situation outside Europe was very different. Extra-European countries were not equal because they didn’t belong to the same civilisation – that is, to the same agreed law system. Therefore, a different set of laws applied: colonialism.
In colonial conflicts applying any law was very difficult. The opposing parts typically adhered to different law systems and therefore understood situations differently. Often, it was problematic for the opposing armies to recognise where the battlefields stood and who the soldiers were. In these wars that often took guerrilla forms, everyone was an enemy, and every field was a battlefield.

The absence of common war laws left a void in the relationship between the opposing fighting parts, a void that most often than not was filled by emotions. Emotions toward an enemy: hate, despise, revenge. The other part, then, ceased to be an honourable opponent to become a hateful counterpart. 

The European Civil War

When WWI broke out, the Jus Publicum Europaeum failed.

At the beginning of the 20th century, European diplomacy had been hard at work for over a century to create a network that would avoid a generalised conflict. But that network had become exceedingly complex, with numerous and intricate relationships interconnecting all nations on the continent – a tight net that was difficult to dissipate. 
When Archduke Ferdinand was killed in Sarajevo and Austria-Hungary declared war on Serbia, the condition for a local European war arose. It wasn’t meant to go beyond it. But then, diplomacies all though Europe tripped over that net, nations that were not related directly to the facts in Sarajevo were dragged into the conflict by their alliances, and what should have been a regional war became a global conflict. 
Historians still debate the deeper causes of the outbreak of WWI, but everyone agrees that nobody wanted, or expected it.

The war still started as one of those regional conflicts. Only slowly, inexorably, the collapse of the Jus Publicum Europaeum started to shaw its effects. The old rules and laws that required the action of diplomacy didn’t apply anymore. That vacancy had to be replaced somehow by the only other law these nations knew: colonialism. 

As colonialism broke into the European space, enemies became the object of hate and scorn. The rules of fair play fell. Winning over the opponent – the enemy – was not enough anymore. A need for conquering arose. The conflict became colonial. It engulfed all aspect of social, civil life. It became a global conflict.

These emotions were at the base of the fragile peace. Rules didn’t exist anymore, so the winners and the losers were hard to recognise. Germany never accepted to be the loser and the cause of the war. 

On this ground, WWII was possible. 

RESOURCES

Enzo Travero, A ferro e fuoco. La guerra civile europea (1914-1945), Il Mulino, Bologna, 2008