Smart people, as well as people who aren't complete idiots understand the concept of "priority".
Since you seem to be a complete fucking retard and completely unfamiliar with the concept allow me to explain.
Priority allows someone to view multiple things as important, but to classify certain things as being more important than others.
For example Lulu views his sister as his top priority, getting revenge as his second highest priority. The Japanese rebellion is part of the revenge, and the revenge is part of creating a peaceful world for his sister.
When he leaves his army at the end of the first season, he did so because the most important thing in the world was taken from him. It wasn't that the other things were not important, it was that she was more important.
Also he didn't throw the troops away, he left them under the command of someone who should have been able to keep things together under normal circumstances.