Byzantine question

Can someone explain to me what just happened? I was playing as the Byzantines, and suddenly I had this pop up. It cleared all my monarch points, took away my diplo idea group that i had filled out to three ideas, and replaced it with maritime??

I'm a bit lost as to what happened. I didn't have low legitimacy at the time and nothing in the wiki mentions this happening. Help?

http://i.imgur.com/n2AUHHk.png