What the the saying you have met the enemy and they are us?

There was a very popular comic strip of the fifties, and sixties called Pogo. It was about Pogo Possum and a bunch of colorful, characters that lived in the Okefenokee Swamp. In one of the strips (I can't find the date it originally ran), Pogo and a friend are standing in front of a place used to dump trash in the swamp, discussing lamentable situation. In the last frame, Pogo says "We have met the enemy and he is us".

They have recognized that the trash befouling their swamp consists of the kinds of things that they all use themselves. The line caught on and it was used for a poster for Earth Day 1970. It has since become a well known saying and a slogan for the "green" movement.

Pogo's line is based on the famous quote of US Navy Commodore Oliver Hazard Perry's report to headquarters upon his capture of the British fleet on Lake Erie in a battle of the War of 1812, "We have met the enemy and they are ours."