I can't remember if it is a trilogy or a single book. But I remember something along the lines of we colonized other planets and such and Earth is now out of contact- no one knows what happened. In the meantime, the main character(s) are fighting either aliens or rebels, I can't remember. There was a general feel of order and government just falling apart, and toward the end the main character(s) try and get back to Earth and they find some messed up stuff that happened- I think the defense system Earth implemented had malfunctioned and no one could shut it down- so no one could leave Earth. That's about all I can really remember. Oh and most of the combat I believe was planetside dealing with infantry and aircraft. If someone could tell me a title or author would be great.