War of the Frontiers

War of the Frontiers
Cacertian infantry attack at the Battle of Adrano
Date 16 March 1885 - 24 September 1885 Location Auroa Knichus Result Acrean Victory
Belligerents
Acrea	Cacertian Empire
Commanders and leaders
Ludvig Vikander Mathias Corriveau August von Braun	Zabina Padula Ariele Adinolfi Doriano Aliberti
Strength
220,000	375,000

The War of the Frontiers was an armed conflict fought between the Kingdom of Acrea and the Cacertian Empire from 16 March 1885 to 24 September 1885. The war was primarily caused by the desire of Elliana I to reduce or displace Acrean colonial control and influence in eastern Siduri and the Bara Sea. The conflict resulted in a swift Acrean victory which halted further Cacertian expansion into southeastern Siduri. Elliana I sued for peace and petitioned the Acreans for negotiations, which Acrean Queen Alyssane II acceded to, eventually culminating in the Treaty of Apridine which would dictate Acrean-Cacertian relations for over 70 years.

Planning for a war with Acrea in Vichenza began in late 1883, a few months before the completion of the conquest of Liriniya in the the spring of 1884. Strategically, Acrea posed several challenges to Elliana I's ambitions for Cacertian expansion. The Acrean colony of Auroa and protectorate of Pteleia created a bulwark against any Cacertian expansion westward on the continent from Knichus, while Acrea's alliance with the Phạm dynasty gave it effective control over most of the eastern seaboard of Siduri. Importantly, Acrea also controlled the eastern mouth of the Sundering Sea; consequently, the Cacertians were effectively blockaded from reaching central Siduri without first dealing with Acrea. Initially, Elliana's government first considered negotiating with the Acreans to ensure open passage through the Sundering. Although considered the easiest and most expedient route, given the neutral relationship between Acrea and the young Cacertian Empire, concerns were quickly raised about how easily the Acreans could cut off this access if relations soured or a war broke out. Elliana's plans for expansion anticipated friction with Acrea, if not outright conflict at some point. Ultimately, Elliana and her general staff decided on pursuing a land route into Siduri through Auroa.

Beginning in 1884, Cacertian troops began arriving in Knichus via Liriniya, using the short sea routes which connected them to Cacerta. A force of some 300,000 was anticipated to be more than enough to overwhelm the Acrean territorial army in Auroa which was estimated at 50,000 troops. Holding much greater confidence in her army after the Liriniya campaign, at Elliana's insistence the plan was to restrict the conflict to a land-based one. She held skepticism in the ability of the Cacertian Royal Navy to successfully engage the larger Acrean fleet in a direct confrontation. With similar concerns held by her commanders, they decided to constrain the movement of the Cacertian fleet to instead protect the sea routes between Cacerta, Liriniya, and Knichus. Although the Cacertians took steps to conceal their troop movements, word eventually reached Rena of the developments via spies in late 1884, prompting the Acreans to begin deploying an army under Ludvig Vikander to Auroa to support the 60,000-strong territorial army under August von Braun. By the time the Cacertian invasion began in March, an additional 40,000 men had been deployed to Auroa.

The Cacertian operation began on 16 March, with a three-pronged advance into Auroa with its invasion force divided into three armies. The Cacertians initially met only moderate resistance, engaging with Acrean advance forces in skirmishes, though nonetheless pushed on. Although substantially outnumbered, the Acrean Army held a few key advantages over the Cacertians, though none more important than its weaponry. Compared to the Cacertians, Acrean forces held two technological advantages: smokeless powder weapons, and the machine gun. The advent of hvittpulver, a smokeless powder propellant, by Acrean chemist Stig Vignes in 1879 led to a rush by the Acrean military establishment to field weapons utilising this new technology in the years immediately after leading to the adoption of the Dessauer M1881. This development coincided with the gradual introduction of the MG m/78 into Acrean service. The first machine gun used by Acrea, the m/78 used black powder ammunition and was intended to replace a variety of rotary guns in Acrean service at the time. Smokeless powder ammunition solved numerous reliability issues related to the older black powder ammunition, and in 1883 the more developed MG m/83 was introduced using the new ammunition. Cacertian forces, used to expeditionary warfare, were fairly lightly equipped with only light artillery and some rotary guns. Acrean forces at the start of the conflict were similarly equipped with only light howitzers and their machine guns, though as more forces arrived from Acrea they brought with them heavier howitzers.

The turning point of the conflict's early days came when Cacertian and Acrean troops first met in a major battle at the strategic town of Aonotena approximately a week after the start of the invasion. Located along a major travel route, Cacertian commander Doriano Aliberti sought to capture the town to secure a location to set up a forward depot, for which it was ideal. Expecting moderate resistance, Aliberti's attack was almost immediately halted when it encountered entrenched Acrean positions by a constant barrage of machine gun fire. Aliberti pressed forward with the attack, attempting a flanking maneuver around the town that was countered by an Acrean flanking force. The grassy, open, flat terrain of southeastern Auroa proved lethal to the Cacertians, as it allowed the Acreans to maximise their range and visibility. After a day of fighting, Aliberti fell back from the attack, with the Cacertians having suffered horrific casualties.

The results of the battle were repeated when the other two Cacertian field armies, led by Zabina Padula and Ariele Adinolfi, encountered similar Acrean defensive positions and in similar terrain. The entrenchements made the positions difficult to counter with their light artillery, while the sustained fire of the machine guns made any assault suicidal. Cacertian leaders attempted to bypass the defensive positions entirely, but quickly became mired down by a combination of Acrean regular infantry and native Aōtean militia. The latter were noted after the fact as being particularly effective when armed with new Acrean rifles, with Adinolfi commenting after the conflict that they inflicted nearly as much damage on the Cacertians as machine guns. Still severely outnumbered, the Acreans were only able to effectively outmaneuver the Cacertians after several weeks of attrition, eventually routing the combined Cacertian armies at the Battle of Teaorongo in late April.