Mankind Declaration Treaty

The "Declaration of Mankind's Common Front Against the Demon Race" or "Mankind Declaration" is a pact treaty that was first set up by the Gran Chaos Empire, with the main goal to unite all human-led kingdoms in order to oppose any expansion by the Demon King. In layman's terms, it is like the United Nations or NATO on Earth. As such, there are three main clauses.

Clause 1

Any border changes due to military action by any kingdom are not acknowledged. In short, should any of the members of the treaty try to annex or capture each other's territories, then it will lead to military intervention by the Gran Chaos Empire to return the borders back to their original positions. This does not include any previous changes in borders before the treaty, such as Amidonia's loss of territory 50 years prior to signing.

Clause 2

Every citizen within each kingdom shall have equal rights and the kingdoms shall respect their individual freedoms.

Clause 3

All kingdoms which are far away from the Demon King's territory shall work as support for the kingdoms that protect them, which are located near the Demon King's territory. If the kingdom cannot pay the war tribute, it can summon a hero and hand him over to the Empire.

Contradictions and Problems
Though this treaty was created with the intent of uniting all kingdoms and to stop wars between nations, it has failed on several counts, due to the contradictions of the first and second clauses. Not to mention that the third clause was the main reason behind the summoning of Souma Kazuya.

The first clause was ignored by the Principality of Amidonia, due to the fact that Elfrieden did not sign with the treaty and therefore, is not protected by it. As such, it was seen by Gaius Amidonia and his son as territory that was free to be invaded and annexed. However, when they lost the One Week War and lost their capital city Van, Julius Amidonia hypocritically called on the Grand Chaos Empire for intervention, even though it was Amidonia who invaded in the first place. Furthermore, since the Republic of Turgis was not a signatory nation, that gave them the freedom to invade Amidonia. The Orthodox Papal State of Lunaria would also use this loophole to invade Amidonia, under the pretense of protecting believers of their faith. With the threat of being forced to leave the Treaty and therefore lose the protection it granted, Julius had no choice but to agree to pay huge war reparations to Elfrieden.

The second clause interfered with the first clause when the citizens of Van and later the whole of Amidonia wished to merge with the Elfrieden Kingdom. Infringing on their rights and freedom would have violated the second clause, even though the first clause did not permit the changing of borders. This was the main reason why Kazuya did not allow Elfrieden to sign the treaty as he saw this major pitfall and likened it to the Helsinki Accords of 1975 on Earth. The Mankind Declaration Treaty may prevent outside conflicts between nations, but internal issues within a nation become intractable. This loophole can also be quite dangerous, as Maria Euphoria pointed out, if the Orthodox Papal State of Lunaria were to incite their believers in the Gran Chaos Empire to gather and declare independence.

Despite not being a signatory of the treaty, the Kindgom of Elfrieden was forced to pay war support, due to the third clause. Since Elfrieden could not afford to pay the amount, they instead enacted the clause to summon a hero and hand him over to the Empire. However, this led to the summoning of Souma, which set the kingdom on the road to economic recovery and reform. After the capture of Van, the nation would again turn down the offer to become a signatory of the Treaty and instead form a bipartite alliance with the Empire.

One thing to note about the third clause is that it was created to appease any resentment by the signatory nations, since non-signatory nations benefited from the protection of the Treaty, without having to commit any troops to defend the border between the signatory nations and the Demon Lord's Domain. In Elfrieden's case, since it did not have the funds to pay for the war support, the summoning ritual was a way the Empire could show consideration towards Elfrieden and appease the signatory nations, since there was really no need for a Hero at present.

If a signatory nation does something that goes against the clauses of the Treaty, or takes advantage of any loopholes for ambitious gain, the Gran Chaos Empire can force that nation to leave the Treaty, thereby causing it to lose the protection of the Treaty. Amidonia was in danger of such a situation when it invaded Elfrieden. Gaius Amidonia was also fearful that the Empire might make his nation into a puppet state due to its actions.

Signataries

 * Gran Chaos Empire (Chief Signatory) & its Vassal States
 * Former Principality of Amidonia (now merged with Elfrieden to form Freidonia)
 * Union of Eastern Nations

Non-Signataries

 * Kingdom of Freidonia (formally Elfrieden and Principality of Amidonia)
 * Mercenary State Zem
 * Republic of Turgis
 * Nothung Dragon Knight Kingdom
 * Star Dragon Mountain Range
 * Orthodox Papal State of Lunaria