introduced chickens at night - but they woke up and started fighting...

They won't be buddy buddy until they work out the pecking order. Just make sure that there is no blood. If there is treat the hen/pulley that is hurt with bluekote. Read up on pecking order. Things will work themselves out. Not just immediately.

 

Sometimes it helps for them to see each other for a little while first.
When I do it, I like to take them in 2 at a time and carry them aroud with the rest of the flock looking at me & the new girls.
Or, if its a posibility, close a screen door and have them in sight but seperated.
After a while I set the new ones down, or open a door. I usually see better results if I'm the one brining them in compared to just opening a door and walking away.

No matter what there will be some fighting, its just what they do and how they solve problems. Limited vocabulary = fights, same thing with people.

As said above just watch out for blood and if you can go out there and be a rooster, break up any fights near the food or nest boxes, but let them have at it if they need to away from the rest of the relaxed birds. Fights can spread fast in the hen house, try to minimise the stress and impact of pecking order adjustments.

 

I once introduced four new hens to my five hens. When they woke up it was like the Bloods and the Crips...fighting all the time. They, eventually, worked out the pecking order and all was good. I now have six hens and four new ones in a coop. I divided the run and set up a temp coop in the divided off section. The new hens are in there. They can see and interact with the existing hens, but are safe from attack. After a couple of weeks, I will put my boss hen in with the new girls. She will work things out with them and become protective of them. Then, after a month, or so, I will put them all together one night.

Yes there will be fighting, but hopefully just for a short while.