Battle of the unknown

Write about a conflict in your world known for being unprovoked or unfair.
Chaos had affected Nitsoba the moment the opposing army had appeared out of seemingly nowhere. The rush and panic that set in while the standing army and groups of adventurers rushed in to protect the city and get their fill of bloodshed. The enemies they fought were mysterious, seemingly affecting the minds of those that saw them to forget about them soon after the fact. The mysterious creatures seemed to have some sort of rusting and rotting affect of those who were poisoned by their attacks, and many died defending the city.
The battle ended in a victory for the City of Nitsoba, as the foes that attacked them were all slain and disappeared as quickly as they arrived. The bodies dissolved afterwards, leaving behind no trace of the attackers. Despite the victory, the city suffered heavy losses and paranoia for the next weeks. Many people began to speculate about the causes of this attack. Rumors of a second attack were quickly spread throughout the city, with many people hiding in their houses for protection.
The only things those with sharper minds could remember was the "army" they fought being of mostly undead abominations, who weren't very tough individually but had such sheer volume and numbers that one could have been overwhelmed quickly if they were not careful.

The Conflict

Battlefield

The battlefield was the City of Nitsoba itself, and the surrounding land.

Conditions

The skies were dark that day, causing it to be difficult to see on the cities side.

Outcome

The city has had to rebuild and elect a new Emperor, which they quickly did.

Aftermath

There has not been enough time for the battle to have had long term effects so far.

Conflict Type

Battle

Battlefield Type

Land

Start Date

Lyc 21st, 10,913

Ending Date

Lyc 24th, 10,913

Conflict Result

The city won, but the Emperor was killed, and a large chunk of the city was destroyed, as well as many casualties.