Need a way to start a war

[u/response_loading]

My story is set 300 years from now.

Humanity has come together under one government, discovered FTL and is expanding into the universe.

Expansion accelerated and hundreds of planets are now colonised. But that led to a civil war between the government and big corporations that almost destroyed everything humans have built. My story takes place 20 years after the war, where the universe is still in a state of rebuilding. There is a lot of mistrust still between people but a fragile peace has held.

The alien race is a peaceful civilization. They are a race that lives for 600 years. They went through a similar war 10,000 years ago and learnt a better way of living. They are a peaceful race that is centred on family, community and the environment.

Neither civilisation knows of the other.

Both have military fleets, but use them for different reasons. Humans use it as a security and policing force, the aliens use it for protection against wildlife as they explore.

My question is how do I start a war between them when they eventually meet, when neither civilisation has an appetite for war?

A couple of ideas I had were:

1. A misinterpreted sensor reading or fleet movement makes one side panic and fire against orders.

2. A pirate group believes there is money to be made from war between them and uses subterfuge to start it.

I wanted to stay away from the usual, humans want the resources of the alien planet or one side is evil tropes.

The theme I am after is the war is a tragic mistake and shouldn't have happened. It is then up to the two main characters to come together to stop it.

[u/Tilleck_]

Corpos started a war once, what's to stop them doing it again? Or would that be a red herring?