Manning was arrested in May of 2010 (no specific day given), the Deep Water Horizon explosion happened on April 20, 2010.
Thanks. That makes things much more interesting. From what I understand, some period of weeks passed from the time Manning (over a period of some time) downloaded the classified materials, to the time that he was arrested.
If Assange has information about the BP disaster, there almost certainly has to be another leak other than Manning given the timing of events. I'm not sure anyone has said this, at least not publicly.