[Bearfootfarm]

You may be able to just "rock" them back and forth to work them loose, but sometimes youll have to dig down on one side to break them free. It depends on how hard the ground is.

If they are 4 X 4 's they dont HAVE to be buried at all, if you put a 2 x 4 base to nail them to. 18" would be fine though for a chicken coop. If you get a lot of high winds its best to set them in the ground at least on the corners

 

[Bearfootfarm]

A chicken run doesnt have to be as sturdy as a fence. I still think it would be easier to build it without setting the posts in the ground. When I built mine , I laid the walls out and built them laying on the ground. It was easier to handle the wire that way, and then I simply stood them up. Im assuming it will be attached to a coop, and that will provide all the support it will need. You can use 6 ft wire instead of 4 ft , and 2 X 4 wire will stretch easier than "chicken wire".

This isnt a great pic but youll get the general idea:

 

[Bearfootfarm]

I took some better pics of the run today. Its 12 X 18, and about 7 ft tall
I used 2 X 4 welded wire instead of "chicken wire" Its stronger and easier to work with. I considered covering the top , but it's been over a year with no losses so I dont see a need for it. I can always do it if a problem arises, but my dogs do a good job of keeping predators out of the yard. I also built a new roost that pivots up out of the way instead of having to move it to clean up

 

[Bearfootfarm]

I don't know where I got it but I wrapped my run with 1.5 x 1.5 inch instead of the easy to find 2x4 ww. Sure wish I could find my source again!

I worry the 2x4 doesn't keep little chicks in nor raccoons out.

The door to my coop sits about a foot higher than the floor. I keep small chicks inside until they are able to get out on their own, at which time they are too big to fit through the wire. No problems so far with anything getting through the wire.