Although it's been known about for a few days, Sierra today officially announced Empire Earth III, the third game in Mad Doc Software's RTS series is due this coming Autumn.

"The Empire Earth series has been the recipient of much deserved praise from the media and fans alike, making it a multi-million unit selling franchise for Sierra Entertainment," said Cindy Cook, chief strategy and marketing officer for Vivendi Games. "Empire Earth III will take the series to the next level with its ability to capture the entire scope of the globe and give it to the hands of the player."

Empire Earth is the only RTS series that allows players to build and rule an empire from the ancient world to the distant future, battling it out across the globe through the eons in a bid for worldwide control. Unlike other RTS games that take away the spoils of victory, Empire Earth III will offer continuous free-form gameplay that will allow players to keep units from one battle to the next.

** Update **
There's a single Empire Earth III screenshot in the gallery, it certainly has received a graphical update since the last game.