Norden Incident

The Norden Incident was a battle between the Imperial Northern Army Group and the Legadonia Entente Alliance Army. It is widely considered the start of the World War.

Background
A long time ago, the Empire and Legadonia Entente Alliance had an unofficial dispute over the drawing of the national border. Legadonia used to claim the territory of Norden, which was under the Empire's control, but the Treaty of Londinium, which was mediated by the Commonwealth, allowed the Empire and Legadonia to resolve their national border dispute by compromising and recognizing a common national boundary. Since it was officially named a provisional demilitarized zone, and was confirmed by the executive government of both nations as a de facto national border, there's nominally no dispute over this territory in the international politics arena. However, multiple isolated accidents still occurred along the border. There were incidents of unintentional fire on both sides, which led to firefights breaking out due to misunderstanding, causing the situation to become tense.

Legadonia Entente Alliance
Legadonia was facing a sluggish economy, widening wealth inequality, and an unemployment rate that refused to fall. These factors finally led to a change in Legadonia’s policies, as well as a regime change. Due to the change in political climate and the installation of new leaders, a rise in nationalism demanded a huge shift in national policies. Since the Empire had territorial disputes with most neighboring nations, most of which formed an alliance against the Empire, the new Legadonian government expected the Empire would make some degree of concession. Once again, Legadonia claimed the territory of Norden as a sort of domestic propaganda. Some government spokespersons even described this military operation as a “highly organized hiking exercise under pressure”. They deployed some infantry divisions at the border and demanded Imperial soldiers to withdraw.

“Imperial soldiers are to withdraw from our nation's territory within twenty-four hours.”

Later on, Entente Alliance further sent the Imperial Army in Norden an advisory.

“Disarm and surrender to the advancing Entente Alliance Army or leave immediately.”

The Empire
The Imperial high command ignored the turbulent situation and judged it to be merely brinkmanship diplomacy, expecting that neighboring nations such as the Republic and Commonwealth would probably fear that their past efforts to help them would be lost and stop their military operations. They even allowed the military academy to send its cadets to Norden for education. The Empire had great military strength that even during peacetime, a corps-sized garrison was deployed to the border under the pretext of routine patrolling. Nevertheless, the emergency warnings came flying in from security outpost positions scattered along the border, alerting the command to the signs that the Entente Alliance was planning to conduct a large-scale cross-border operation. 24 hours before the breakout of Norden Incident, the local Imperial army was ordered to stand by for 48 hours.

After received the demand to withdraw from Entente Alliance, the Imperial Army followed the plans laid out by their country, mobilizing the cautious bureaucracy and military arm in preparations for a theoretical attack. In preparation for war, an additional corps was formed by mobilizing troops that weren’t part of the garrisoned forces. They gathered large amounts of resources and mobilized units here, inviting press from other countries and permitting them to stay in Norden.

Invasion
One day in June, 1923, the Entente Alliance forces crossed the border at multiple locations. In response, the Empire declared war on Legadonia Entente Alliance. The Imperial artillery bombarded the Entente Alliance Army by air bursts and time on target missions, and Imperial armored forces and other troops rapidly deployed on the front. The Imperial air forces built an air defense network that was properly set up, with air units and mages ready to intercept. In contrast, the Legadonia Army was in utter chaos. They crossed the border without properly transitioning to a war footing, assigning the wrong frequencies to their signalers. Awful crosstalk occurred between the forward controller and the combat units which weakened their capability for unified resistance. Later, the Entente Alliance invading forces had been destroyed.

Besides, when the Empire was about to switch to the offensive and pursue the enemy forces, a Legadonia aerial mage company broke through the Empire's air defense line, and attacked an Imperial mage observer. The Imperial mage observer got heavily injured yet successfully kept them from attacking the Imperial artillery position. This mage observer sooner was awarded the Silver Wings Assault Medal for her excellent performance.

Aftermath
Although the Empire had already defeated the invading forces, meeting their national defense objectives, the General Staff decided to mobilize the entire Great Army, launching a major offensive against Legadonia. The Imperial General Staff attempted to finish off the Entente Alliance once and for all, and overrated the flexibility of Great Army. This decision finally led to a series of wars that are known as “The Great War” in future.

Reference
Deus lo vult - Chapter I The Sky In Norden.