Edit: Frank Mentzer revealed the following on the origins on the original edition of Chainmail:
"I believe that Jeff was the sole Compiler/Author of Chainmail (the version for the club, gathering various good ideas and massaging them into coherence). For publication, Gary had to give it more work. I also believe this fact is vastly overlooked."The original version of the ruleset was distributed in 1970, while Guidon Games published their 1st edition in 1971. TSR published their first version (3rd edition) in 1975 (Acaeum).
For a while, many incorrectly assumed that Blackmoor was simply a variant of the Chainmail game, but although I think that most people these days accept that that is just a myth, gaming historians and fans still debate to what extent Chainmail did influence the two creators of Dungeons & Dragons. My friend DHBoggs has written som excellent articles about this on his blog here.
No matter where you land on those debates, I think we should all be able to recognize that Chainmail was an important milestone in the development of our hobby and we can be thankful for Jeff Perren's contributions. In this short interview, Perren humbly admits that he recieved no royalties for Chainmail, but that he is happy that some of the things he created are still loved. The World of Greyhawk also has a region, Perrenland, that is named after him.
Happy birthday Jeff!
Note: Image taken from this blog
Note: Thanks to author Matt Forbeck for making me aware of the date of Mr Perren's Birthday.
More discussion of this topic at The Comeback Inn