Mid-East Allied Forces

The Chūtō Rengō (中東連合) is a nation consisting of a coalition of various territories. They are enemies of Marley who were at war with their nation for four years after the warriors' failure to capture the Founding Titan, though the Allies eventually lost the war and presumably lost autonomy of their nation.

Geography
While little can be said of the climate or exact location of the Mid-East Allied Forces, it is said that the nation was located on a peninsula.

Military
The Mid-East Allied Forces are superior in some instances to their enemy nation of Marley.

Being the defender in the battle of Fort Slava, the Allies make use of water-cooled machine guns and heavy artillery installed on the fort's towers to fend off the Marleyan assault. Additionally, its troops are well sheltered in concrete bunkers.

The Allies were acutely aware of the threat that Titans pose. For example, Allied soldiers were willing to fire on a seemingly unarmed and surrendering Gabi, simply because they suspected that she was an Eldian and might turn into a Titan in any moment. Perhaps the best example that illustrates the Allies' concern of that threat was the anti-Titan artillery which it developed. Designed solely for the purpose of fighting Titans, it fires 100mm armor-piercing shells which are capable of destroying even the Nine Titans. The guns are fitted on an armored train, which moves on a railway network built around the fort to ensure rapid deployment of the guns.

The Allies presumably had a strong naval force before the battle of Fort Slava, as warrior cadet Udo mentioned that it took four years for the Marleyan navy to control the sea with almost half of its fleet lost.

Marley arc
After Marley lost the Colossus Titan and the Female Titan during the Paradis Island Operation, the Mid-East Allied Forces took advantage of their enemy's weakened military capabilities and declared war on Marley. Over the course of four years, the Mid-East Allied Forces gradually lost their advantage against the enemy, losing control of the seas by the time of the battle of Fort Slava. The Allies' navy, however, dealt significant damage to the Marley navy in their naval battles.

At some point before or during the war, the Allies develop the anti-Titan artillery, a heavy cannon designed to kill any Titan in a single shot, even one of the Nine Titans.

After four years, the Allies make a final stand at Fort Slava, a fortress equipped with heavy machine gun defenses and anti-Titan artillery overlooking their last naval station. Commander Magath of the Marley military leads a siege against the fort alongside an 800-man unit of warrior cadets, with their warriors kept on standby, as Magath is unable to use them due to the anti-Titan defenses implemented by the Allies. However, when cadet Gabi destroys the armored train carrying artillery around the fort, the Allied soldiers are attacked by the Jaw Titan and "Cartman", the Titans of Porco Galliard and Pieck. Soon afterwards, once the outer defenses of the fort are destroyed, a zeppelin overhead carrying Zeke Yeager and Reiner Braun releases dozens of parachuting Eldians above the fort which Zeke turns into Titans using his Titan powers, raining devastation down upon the Allies. When all the Titans are killed, Reiner's Armored Titan and Zeke's Beast Titan finish off the remaining artillery guns, and Zeke tosses spare rounds at the fleet in the nearby bay, destroying the last of the Allies' fleet and ensuring victory for Marley.

A peace treaty is signed after the Allies' defeat at Fort Slava, and the Mid-East Allied Forces presumably lose their autonomy following the war. However, other nations opposed to Marley praise the Allied Forces for their success with the anti-Titan artillery, signalling the coming of the age when mankind has overcome the power of the Titans. Survivors of the battle of Fort Slava are later sent home traumatized to serve as a reminder of the Eldians' demonic nature.

Trivia

 * Given the fact that the Mid-East Allied Forces are said to be located on a peninsula that lost its political autonomy, it is possible that the nation is located either on the peninsula resembling a mirrored or the peninsula resembling a mirrored  in the southeastern region of Marley as displayed on the map in Chapter 93.
 * Their uniforms resemble that of Ottoman Empire during World War I.