Pact of the Sword of Fire

The Pact of the Sword of Fire is a chivalric, mutual defense pact formed between several Imperial worlds in the Segmentum Pacificus and Western Segmentum Solar for the purpose of managing the myriad threats (primarily Chaotic in nature) that threaten the least populated and one of the more tenuously held regions of the Imperium of Man outside of the Imperium Nihilus. Its members are sworn by sacred oath to come to the aid of each other when any member comes under attack, and to enforce the will of the God-Emperor of Mankind (or the Omnissiah, according to the oaths of its Adeptus Mechanicus members) as well as to share intelligence, resources, and other aid between each other.

History
The Pact was initially formed as a brokered peace between the Astral Leviathans of Karthas and the Adamant Wardens of Brigg after an invasion of a world uprising in a Tzeentchian heresy was subdued by a force of Ordinators, Astral Leviathans, and Adamant Wardens during which an Astral Leviathan murdered an Adamant Warden. At the brink of war and knowing the stability of the region was in dire threat, the Legatus of the Ordinators, Ozydorax Pharseus diplomatically brokered a peace between the two and asked each to swear an oath on behalf of their chapter homeworlds to come to the aid of the other whenever asked. Joining on behalf of his own homeworld as the Lord of Azuran, Legatus Pharseus began to seek other allies within the sparsely populated and significantly threatened Segmentum Pacificus as well as the Western border regions of the sacrosanct Segmentum Sol to ensure an alliance capable of ensuring peace in the sectors of the Western reaches of the Imperium could emerge. By the time of his successor, Legatus Aureus Magus, the pact had evolved into more than a mere military alliance with the introduction of the Forge World of Ferunus and the Feudal Agri/Knight World of Tharan V. Providing foodstuffs, water, material aid, and sharing intelligence became core functions of the Pact - and the security of the alliance's worlds increased significantly as a result of the subsequent insurance to have their needs met. As more and more planets joined, the ability of the Pact to provide for its member worlds increased. Specialized astropathic relays were established to improve communications, and charters of trade for the transportation of goods between member worlds became more and more common, allowing multiple means of transport of aid and personnel between the members of the alliance.

In the coming of the 42nd millennium, the Pact came to maturation. Each member world began to send delegations to meet on one of the member worlds every decade, and weekly communication occurs between each member apprising the others of their current needs, security risks, and any outstanding requests. Any wars fought against one member now necessitate the involvement of many hundreds of thousands or even millions of Guardsmen, Skitarii, Adeptus Astartes, and various support personnel.