Electronic Arts has announced that all Battlefield 4 expansions packs are available to download for free from September 14 until September 19 across all platforms. You only need to download the expansions to keep them forever.
"As we approach the end of the road, we've got something really special for anyone looking to get some Battlefield 4 action in before Battlefield 1 ships on October 21", said Electronic Arts. "From September 14 until September 19, every expansion pack for Battlefield 4 is now available for free. That's right, all of "˜em. And we've even got themed Community Missions to go along with them."
You can find more details on the Community Missions on the Battlefield Blog.
Source: Battlefield Blog