Second, draft 50 soldiers. This is plenty of soldiers to attack with when protection ends.
Third, build lots and lots of shipyards so that when protection ends you will have a huge navy to defend your land.
Then if you are regent, declare war on everyone so you have a big attack bonus when protection ends. You don't need to worry about defense cuz your navy will protect you. Tell your regent to do this if you aren't regent.
Then have your regent start a dragon against the most powerful kingdom in the world. You get more land for attacking powerful kingdoms and your navy is strong enough to protect you from retaliation.
When protection ends attack the biggest province on the kingdom you sent a dragon to with all your soldiers. Your navy will go with them to attack so you will win for sure. Your navy comes back right away to defend so don't worry about that.
Now you will get even more land and you will be the most powerful in the world. You can figure out what to do now.