Marley Mid-East War

The Marley Mid-East War was a conflict between the nations of Marley and the Mid-East Allied Forces on the continental mainland following the failure of the Paradis Island Operation. The war resulted in the surrender of the Mid-East Allied Forces, and Marley's need to acquire the Founding Titan was more fully realized after witnessing the destructive power of anti-Titan artillery.

Prelude
In Marley's operation to take the Founding Titan from the royal family of Paradis, their mission was met with failure. Not only were the warriors unsuccessful in taking the Founding Titan, but the Female Titan and the Colossus Titan were lost during the Stohess District raid and the battle of Shiganshina District, respectively. With the loss of two Titans, Marley's military capabilities were greatly reduced. This loss of power was noticed by the Mid-East Allied Forces, a coalition of territories against the nation of Marley, and thus war was declared in the year 850.

Naval conflicts
While the specific events of the war between Marley and the Allies are unknown, Marley successfully gained the upper hand over the Allies over the course of four years. A significant portion of the combat took place on the sea, where Marley slowly pushed back the Allies' fleet and gained control of the waters. However, the naval battles were evidently poorly fought, as Marley had lost over half of its navy during these four years.

While Marley and the Allies fought for control of the seas, the Allies also began work on the anti-Titan artillery, cannons with 100mm armor-piercing shells capable of killing any Titan, even one of the Nine Titans, with a single shot. While this weapon would not be seen until the last days of the war, it nonetheless posed a significant threat against Marley's military, which heavily depended on the power of the Titans.

Battle of Fort Slava
In the year 854, Marley had succeeded in pushing the Allied fleet to the naval station near Fort Slava on the coast of the mainland. At the request of the navy, ground forces were sent to take over the fort before Marley's fleet could advance upon the Allies' fleet stationed in the bay. While the Titan warriors waited on standby, Commander Magath of Marley's military led a unit of 800 warrior cadets in a siege against the fort. Trenches were dug by the cadets in order to avoid the machine gun defenses placed around the fort, ensuring a slow but guarded advance. Late into the siege, the front unit of the warrior cadets was hit with explosives, bringing the trench advance to a halt.

Cadet Colt Grice suggested to Commander Magath that they should send out Titan warriors Porco Galliard and Pieck, the Jaw Titan and "Cartman", to attack the Allies' defenses, but the suggestion was denied due to the presence of the anti-Titan artillery mounted on armored trains on the railways surrounding Fort Slava. Seeing an opportunity to prove her worth as an inheritor of the Armored Titan, Cadet Gabi approached the defense bunkers in plainclothes feigning surrender, secretly carrying a bundle of grenades with her. When the train approached, she tossed the explosives at the head of the train, derailing the weapon as the bunkers opened fire once more. With the artillery out of commission, Magath sent forth Galliard to attack the Allies' defenses. As Galliard's attack on the Allies began, the ground infantry signaled Marley's nearby zeppelin of the destruction of the armored train. The Jaw Titan continued to assault the Allies' defenses while Pieck's armor-plated Cartman provided supporting fire. When the outer defenses of Fort Slava were adequately destroyed, the zeppelin dropped restrained Eldians in parachutes over the battlefield for Zeke Yeager to transform into Titans with the power of the Beast Titan. The Titans acted as a devastating airstrike, decimating much of Fort Slava and a significant portion of the Mid-East's defenses, though 60% of the Titans died from the fall. With around 30 anti-Titan cannons still operating, Reiner Braun joined in the ground assault and attacked the remaining defenses as the Armored Titan alongside Galliard's Jaw Titan.

The two Titans made quick work of the remaining defenses, and shortly afterwards Zeke joined the ground forces as the Beast Titan, using the Mid-East's own artillery stockpile as projectiles against the navy stationed in the bay near to Fort Slava. The fleet was completely destroyed, though Reiner's Armored Titan was severely damaged by the fleet's artillery. With the Mid-East Allied Forces' fleet in ruins, all defenses against Marley were spent and the war was won.

Aftermath
The Mid-East Allied Forces possessed no remaining defenses against Marley after the devastating loss at the battle of Fort Slava. Therefore, the Mid-East had no choice but to sign a peace treaty with Marley, the victors of the war.

Despite their victory, Marley's position as the dominant nation of the world was greatly threatened with the new existence of anti-Titan artillery. Realizing the age of the dominance of Titans over the world, it became clear to Marley that the acquisition of the Founding Titan was a necessity now more than ever. The matter was discussed among the leaders of the Marley military shortly afterwards, where it was concluded by Commander Magath that Marley's reliance on the Power of the Titans has left them at a significant technological disadvantage, whereas other nations of the world have progressed rapidly through efforts to overcome the Titans. Zeke Yeager proposed resuming the Paradis Island Operation so that Marley could gain complete mastery over the Titans while simultaneously developing conventional weapons to maintain their global political hold.