I'm back from Ottawa, but it's going to take a few days to pull myself together and collect my thoughts. In the meantime, here is the 1969 Pogo Special Birthday Special, written by Walt Kelly and directed by Chuck Jones. Kelly and Jones also provided several voices for this.
I know from talking to Kelly's widow Selby that Kelly was disappointed in the results of the collaboration. It was because of this TV special that Kelly and Selby started their own animated short, We Have Met the Enemy and He Is Us.