Board Game Arena

I have a game going. I was at 20 military, my opponents were at 19 and 6. I declared a War over Culture against the player at 19 since I had Air Forces in my hand and we had already beaten on the 3rd place player enough. When I submitted my turn, Air Forces with Classic Army got me up to 31 military. I didn't think the second place player could match that. He did, he also got up to 31 military. However, when it came to be my turn again, I had lost the war as the game thought I only had 25 military. How can you lose 6 military in a War over Culture?

Thanks!

Figured it out. Napoleon died. In between my turn and his turn, the age changed and Age 2 leaders were removed. Bad timing!