The First Armageddon was an ancient event that occurred from a time before history and led to the creation of the Bayonetta universe. As a result of an unequal balance of light and dark, and a subsequent struggle between those forces, the First Armageddon caused the destruction of the previous universe and created the newer, current one. As a result, the Trinity of Realities was formed when the First Armageddon split reality itself into aspects of light, darkness and chaos.
Background
The precise details of the First Armageddon are lost to history. No-one knows exactly what the described "struggle" was or how it ended up creating the Trinity at its conclusion. All that is known are its effects on the world.
After the world of chaos was created alongside the realm of Paradiso and Inferno, its eventual ruler Aesir, the God of Chaos, came forth to bring order to that chaos and the humans who lived in it. As a gift to humanity to maintain the balance of light and dark and prevent the new universe from facing a second Armageddon, Aesir used his power to create the Eyes of the World, ancient powers which were used to create history and defend the just passing of time. Each Eye was entrusted to humanity's instincts: the Right Eye of Light, eventually entrusted to the Lumen Sages and the Left Eye of Darkness, eventually entrusted to the Umbra Witches. However, the balance they strove to keep with the Eyes was toppled by the birth of a half-breed child, leading to a series of battles between the clans and their eventual destruction.
The First Armageddon is not explained in great detail until Temperantia gives Bayonetta information on why the angels are determined to ressurrect Jubileus, explaining how the event sealed her away and how the Eyes of the World would be needed to reawaken her. Later, after Bayonetta is about to be used as the Left Eye in Jubileus' awakening, Jeanne tries to save her and is almost stopped by Balder. He warns that unless both Eyes remain, the universe would lose it's balance and face another Armageddon. Though initially thought to be just related to Jubileus' ressurection, Balder's warning would have more relevance to the future than either Bayonetta or Jeanne would believe.
After Balder's death and the loss of the Right Eye, natural disasters around the world began to unfold at an alarming rate. Around this time, Bayonetta would also lose control of one of her summonings and allow the demon Gomorrah to send Jeanne's soul to Inferno. During her later journey to save Jeanne, she learns that the two events are linked to the balance of powers becoming unstable thanks to the influence of the Right Eye being lost from the world forever, realising that the world may eventually be facing another Armageddon like the First. It is only near the end of her journey to Fimbulventr that the balance is restored and the Armageddon is prevented after Loki, half of Aesir, is able to destroy the Eyes and allow the balance of the world to be entrusted to human hands alone.
