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
Matthias Vaernes
Strength
240,000	325,000

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 Matthias Vaernes 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.