That's very strange. I didn't know everyone on Yavin IV, so I can't say anything on that part, but the rest is strange. Leia has been part of the New Republic government since its beginning, and she was its High Councillor for a while, but she hasn't been doing any military work for a long time. The only military member of her family now is her daughter, Jaina, who's with Rogue Squadron. We continued to fight the Imperial Remnant for a time, but then we were able to sign a peace treaty. The invasion came a few years later.
Master Obi-Wan said there was someone here who might know more about what's going on...I was intrigued by the time travel, but maybe this Doctor can explain this as well.