Simplify the following text for a Grade 7 native English-speaking person.
Original: Battlefield 2s first expansion pack , Special Forces , first began its development sometime during or shortly before the release of the original Battlefield 2 by DICE Canada : Battlefield producer , Mike Doran , commented in August 2005 that `` The truth is that work on Battlefield 2 : Special Forces began several months ago . '' .
Simplified: Battlefield 2 is the sequel of Battlefield 1942 and Battlefield Vietnam . The most recent game of the Battlefield series is Battlefield : Bad Company 2 .