Patch 4.0 - Famine and Troop Desertion
With lords and ladies up and down the nation supporting vast armies filled with hungry troops, farmers have been under more pressure than ever... and the crops can simply no longer keep up!
Famine is striking the nation, so if you can't feed your troops, they'll have no option but to desert and look elsewhere to escape the famine.
When a city has 0 food, approximately every hour you will lose 0.5% of your troops - both from your city and from any armies you have at that time
The exact time at which the troop desertion happens is randomised, to reduce an exploit where a clever player could figure out when the desertion period is due and buy a small amount of food just to cover that period. Desertion happens between every 40 and 80 minutes to a city with no food in it
Having seen the danger, the central government has granted every city 1 billion food to buy their leaders some time to plan ahead. Other than that... you're on your own.