The series first began in 1999 with Medal of Honor (1999), the first game in the series. The game was developed by Dreamworks Interactive, with a story by filmmaker Steven Spielberg. The game was released for the PlayStation on October 31, 1999.
http://www.gamespot.com/search/?qs=medal+of+honorMy input:
With MoH and CoD I really loved the WWII ones. My first game of this sort was MoH on PS1 and I loved it. I loved it so much, it was an awesome game. The best scene was that in the desert with boxes around and a silenced pistol. Frankly all of the WWII games were awesome to me, but the one that I really really loved was "Pacific Assault".
The way they shifted from WWII combat to modern warfare was a bit sad for me. It is much more fun to play in WWII.