Origin: WW3 started when the major villains came together and formed the Enclave. Cap then had no choice but to create a team of highly trained killers and soldiers. This team is called the Secret Invaders.
@ellie_knightfall: Like what Slim said Latour's run is pretty good. I would recommend reading it.
@slimj87d: The series was still selling over 25,000 copies and only dropped to 20,000 - 21,000 when Latour took over. I don't think Marvel canceled the series because Latour are because of sells. I think they canceled the series because of the movie. They probaly want to wait until the movie is closer to release date and then bring a new Winter Soldier series out