Airdale War

{{Infobox military conflict | conflict = Airdale War | width = | partof = | image = | image_size = | alt = | caption = | date = 13 May 1918 – 23 November 1921 (1918-05-13 – 1921-11-23)
(3 years, 6 months, 1 week and 3 days) | place = Airdale, Estmere | coordinates = | map_type = | map_relief = | map_size = | map_marksize = | map_caption = | map_label = | territory = Status quo ante bellum | result = Estmerish victory

• Estmere remains in control of the Airdale
• Swetanian Revolution

| status = | combatants_header = | combatant1 = Sunrosia

| combatant2 = Estmere

| commander1 =

• Adalbert XX
• Rudolph von Waldriek
• Prince Waldemar
• Eugen von Strakonitz-Petrasch
• Paulus von Kalwis

| commander2 =

• William III
• Clive Thompson
• H.K. Rushford
• Benedict Roberts †
• Percival Salter-Smyth

The Airdale War, also known as the Estmerish-Sunrosian War, was a military conflict between the Sunrosian Monarchy and the Kingdom of Estmere. Lasting from 13 May 1918 to 23 November 1921, the conflict was primarily caused by Sunrosian claims to the Airdale region, lost to Estmere in the War of the Triple Alliance.

On 6 May 1918, the Sunrosian government of Rudolph von Waldriek issued an ultimatum to Estmere, requiring the cession of the three border counties of Ashdale, Bardonshire, and Gulval within 48 hours. A general mobilisation was ordered on the same day by Sunrosia, confidently expecting a negative answer. On 8 May 1918 at 4 PM, as the deadline ran out and the Estmerish government failed to answer positively to terms of the ultimatum, the Sunrosian Monarchy officially declared war on Estmere, with several Sunrosian units having already started hostilities an hour early.

The Strakonitz doctrine - the Sunrosian strategy - was to penetrate as deep into Estmere as possible beyond the contested Airdale in the initial assault, with the aims of forcing the Estmerish government into seeking peace, conceding the Airdale and paying war reparations that were necessary to the heavily indebted Sunrosia after the Great Collapse. Having prepared for that exact conflict, Sunrosian forces were able to occupy a fifth of Estmere including the major cities of Lumbridge and Morton within the first five months of the war. By November 1918, a series of successful Estmerish counter-offensives along the Selmrer and Cox rivers turned the tide of the advance and forced the Imperial Sunrosian Army to retreat west; towards a line of fortified trenches. Hopes of a quick Sunrosian victory were ended as Strakonitz doctrine was left in ruins.

By January 1919, both sides had dug into a matching pair of trench lines in eastern Estmere and the war devolved into a war of attrition. While pre-war technological advances had allowed for the creation of stronger defensive systems, that development went unnoticed until then: offensives employing massed infantry advances and massive artillery bombardments suffered severe casualties as they ran into entrenchments, barbed wire, machine gun emplacements and return artillery fire. The front lines remained stable throughout 1919 and 1920 despite multiple bloody attempts at breaking the stalemate, most notably the Battle of Varrock in September 1919 with a combined 700,000 casualties, and the Battle of Princeton in April 1920 with over a million casualties.

In February 1920, the Estmerish launched the Roberts-Rushford Offensives, on the northern and southern part of the front respectively. The twin offensives were the first to feature large-scale use of landships, allowing for unprecented breakthroughs and were highly successful: Sunrosian forces were almost expelled from Estmere by June. With internal troubles rising and casualties accumulating, the Sunrosian military concluced on a final counter-offensive under Paulus von Kalwis, aiming to gain a favourable position to end the war on. Using of infiltration tactics, military aviation, panzers, and poison gas, the Sunrosian forces succeeded in regaining most of the territory lost in the previous offensives by October.

However, the Sunrosian victory would be shortlived. Facing massive mutinies in the army, anti-conscription and anti-war protests throughout the entire country, a Gaullican ultimatum to cede contested territory, and nearing economic collapse, Waldriek was forced to resign and his successor Kaspar von Stenhofen sought immediate peace with Estmere. The Armistice of Warminster was signed on 23 November 1921, although hostilities sporadically continued for two more days, and Sunrosian forces retreated to the pre-war border. The war officially came to an end two weeks later with the signing of the Treaty of Rimmington, essentially concluding the war with what amounted to a status quo ante bellum with neither side obtaining concessions from the other.

Estmere, despite technically winning the war, couldn't gain anything out its victory, and had its weaknesses exposed to the world yet would fail to act on them in time. The massive casualties suffered, coupled with the legacy of the violent occupation of Western Estmere led to a low will to fight for fear of experiencing a similar conflict when Gaullica invaded in the early stages of the Great War. In the Sunrosian Monarchy, the internal situation would continue to deteroriate with the anti-war protests that had gotten violent following the Leneys Street Incident in the last month of the war culminating in the proclamation of the the Panswetanian Council Republic on 30 November and a successful socialist revolution by January 1922.

The Airdale War was the first major war between industrialised powers in the 20th century, and showcased numerous doctrinal and technological military developements, msot notably the birth of military aviation. Military attachés served as observers with the forces of both side, and brought home knowledge of the conditions in which a modern total war would be fought - to such an extent the war is often called a dress rehearsal for the Great War that would take place a mere six years later.