The War of the Gods was a cataclysmic war between the gods of various pantheons. The war itself was long, hard-fought, vicious, and utterly chaotic and described, as well as feared, as one of the greatest and destructive wars in history if not creation itself.
The catalyst behind the war is none other than Loki himself, the Norse trickster god. However, it is unknown what Loki's end game was to spark such a battle between the gods whether it be for his amusement or some darker purpose. Either way, no one is certain as the trickster has quite the complicated mind.
Not long after the imprisonment and defeat of the Great Old Ones, the gods of many pantheons created the Council of Godheads, where they gather and discuss matters revolving around the planet in which they rule or even a section of the universe that is owned by them specifically. The War of the Gods occurred sometime after the formation of the Council, and as such the relationship between the deities was not exactly positive in a sense as there was much animosity and disrespect between these beings due to their arrogance and pride. Loki saw this as an opportunity to create some mischief between the gods, seeing their constant bickering as amusing.
Loki began by slithering his way to Mount Olympus and took the guise of Thor, the god of thunder. While Zeus was away performing his duties, Hera was left by herself in the bedroom. Loki, disguised as Thor, sneaked his way inside and began to seduce the queen of the gods. At first she rejected his advancements but eventually she relents as the two then share an intimate moment. But before it could go any further, the pair were discovered by Apollo who reported the incident to Zeus. Loki immediately left the scene before the king of the gods could arrive. Enraged, Zeus took it upon himself to visit Asgard, the home of the Norse gods and have a confrontation with Thor.
Returning to the land of the Norse gods, Loki, still in the guise of Thor, approached the god of thunder's wife Sif. Believing him to be Thor, Sif allowed him to bed her but after their night together, Loki shifted his appearance from Thor to that of Zeus, traumatizing Sif and thinking that she was seduced by the Greek god. Upon this reveal, Thor too was particularly enraged by this act. It was not long before the king of the gods and the god of thunder encountered each other and initiated their battle. The battle between the deities was said to have shook the continent itself, creating massive chasms that swallowed entire villages.
Odin was quick to stop the fight by tossing his spear at Zeus, briefly incapacitating the Greek god. Demanding an explanation, Zeus claimed that Odin's son attempted to bed his wife Hera, but Thor rebutted by saying that Zeus disguised himself as the god of thunder and had an affair with Sif as a result. Even though both professed innocence, Odin would find himself agreeing with Thor, not because he is his son, but because he is well aware of Zeus' libido acts with many mortal women. Zeus was infuriated despite professing that he had not slept with Sif, and continued to insist to no avail. The king of the Greek gods realized that the only way the Norse gods would listen is through battle and not mere words, as a result he declared war.
The Norse deities accepted and the two factions prepared for battle. It was not long before the Egyptian gods took wind of the declaration of this war, and grew concerned that the warring factions would disrupt the balance of the Natural Order as deities of different pantheons fighting each other is considered a taboo. Horus suggested that they should attempt to discuss the matter civilly but Set disagrees as he reminded him that both the Norse and Greek gods are too proud of their might and strength to listen. Having no other choice, the Egyptian gods prepared for battle themselves in an attempt to stop the two pantheons.
Eventually, the three pantheons became prepped for the battle and collided, resulting in a war that was said to have shaken the very Earth itself. Dark clouds encompassed the globe, completely blotting out the sun, earthquakes rattled and destroyed entire mountains, tidal waves of enormous size drowned both islands and cities alike. The Egyptian gods were attempting to stop both the Norse and the Greek gods, but they would either be countered or pushed back while the two returned to their respective quarrel. The Japanese gods noticed that the war between the three pantheons was putting their kingdom and people at risk, and thus joined in in order to stop the three factions.
The addition of the Japanese gods added further destruction to the planet. According to legend, the war lasted for around seven years with neither pantheon gaining any ground as the chief gods rivaled each other in terms of power and strength. It was not until Vishnu stepped in and demanded the presence of the three chief gods of the Greek, Norse, and Egyptian pantheon. Meeting up with Vishnu, the three gods explained what has occurred and why the war began. Vishnu, however, simply laughed and stated that the war is nothing more than a squabble between children who hold grudges and spite against each other over pride and arrogance. Using his insight, Vishnu revealed that the 'Thor' that seduced both Hera and Sif was in actuality Loki in disguise.
Shocked and humiliated, Zeus and Odin ordered a cease fire. The two god kings sorted out their differences and both agreed that because of Loki's action, he would be met with an unthinkable punishment. But after this, Vishnu informed the gods that they themselves would have to face consequences for their reckless and infantile behavior, like declaring war rather than resorting to finding out the truth of this as a pantheon that battles another pantheon is a taboo and a serious crime in the cosmic order. Zeus found Loki and punished him by having Cerberus chew and gnaw on his soul for six hundred years causing unbearable agony.
Afterwards, Zeus and Odin were stripped of their power and were forced to walk the Earth as mere mortals while Athena and Thor took their thrones and ruled in their stead when they regain their power back from Vishnu. The Egyptian gods were spared from this fate due to simply attempting to stop the former warring factions along with the Japanese gods. All this while Vishnu healed the Gaia as she was in great pain from the aftermath of the seven year long war, and would have collapsed should the battle have escalated any further.