Nationwide Transmutation Circle

A Nationwide Transmutation Circle is made by digging a circle around a nation, and by creating battles/wars/massacres in the Nationwide Transmutation circle, where the key points in a Transmutation circle are. In all known FMA history, only one Nationwide Transmutation Circle had been completed and initiated, which was in the city of Xerxes. Another transmutation circle had been dug in Amestris, and Edward and co. are fighting Father to prevent another Xerxes-like incident from happening.

Purpose
So far, the Nationwide Transmutation Circle had only been used for creating an incredibly powerful Philosopher's stone. There are so many souls inside the stone that the user is basically rendered invincible! Everyone during the process will have their souls removed, killing them, except for those standing in the very center of the circle. Those in the center will then become immortal, and will be turned into living 'philopher stones'.

Xerxes
In the case of Xerxes, the Nationwide Transmutation Circle was dug out unknowingly by the citizens of Xerxes. Father initially couldn't do anything about digging the circle, that is, until the King of Xerxes asked Father if Father knew how to make the King immortal. Father then craftily tricked the King into digging a large ditch around Xerxes, and had the King massacre people in certain places around Xerxes. Those 'certain place' were the places where key points are in a transmutation circle. Once the circle was completed, Father secretly stood with the young Van Hohenheim in the dead center of the circle. The King was near them, but however was a bit further away from the circle. Once the process was completed, Father and Hohenheim both became invincible, whereas everyone else in the city was killed.

Amestris
When Hohenheim had fled to Xing, Father created a new city to the west of the ruins of Xerxes. He then called the city Amestris. Afterwards, when more people entered Amestris, Father had the Military and the State Alchemists founded. Then on, the Military bases of Central, North, South, East, West etc. was created. Father then created his own den underneath Central, where he created the homunculi. He then corrupted the higher ups of the Military, and told them about the secret to invincibilty. Father then had the homunculi assume special roles:

Sloth: Ever since he was created, Sloth was already digging a large underground tunnel around Amestris, which meant that Father created Amestris so that another powerful Philosopher's stone could be created.

Pride: He was the second homunculus created, and mainly assumes the Role of King Bradley (wrath)' son, to make Wrath seem human like.

Wrath: He was to be the president of Amestris and the leader of the Military. Only Homunculi to be able to age.

Gluttony: He was first tasked with destroying the rest of Xerxes with his fake Door of Truth. Afterwards, he didn't really have anything to do.

Lust: Mainly tasked with supervising Gluttony, who was obedient to Lust.

Envy: Started a few wars and massacres in the key points of the Nationwide Transmutation Circle. I.E Ishbalan Civil war: Envy disguised as a military soldier and shot an Ishbalan Chile.

Greed: Betrayed and left the homunculi before the FMA series start, as he thinks that by following Father his greed will not be satisfied. Later killed by Father. 2nd Greed resurrected in the body of Ling Yao.

Currently, the 1st Greed, Envy, Lust, and Gluttony are dead. Pride has lost his shadow powers. Wrath is injured, and fighting a losing battle against Scar. Greed is helping the Briggs military in defeating Central's soldiers.

Edward, Roy, Alphonse, Mei Chan, Hohenheim (absorbed by Father), Izumi are fighting Father.