The reason I never surrender 

A good rule of thumb is that if you are the worst player in your team then you should never be the first player to resign and that better players may be more liberal when resigning.  If the lowest player in the team is doing poorly then the team may still win. If the highest player in a team is doing poorly then it is very unlikely your team will win. Here, it appears you were the lowest player--you should've waited. 

I'm making a few improvements now. Now we have the possibility, when the AI attacks your province, of losing or winning in the auto-resolution. Also, when you lose your last province, a Game Over page appears and we have a button to start a new campaign.      

I am a new player, new to this kind of game as well, any tips and perhaps youtube videos?