Interdicting supply to sevestopol is trivial...the luftwaffe automatically sinks supply points they can reach along the supply trail. All you have to do is wait for the effects of being out of supply to kick in.
Because it is so trivial, I turned on the hardcore supply rule, and wrote an event that automatically puts 300 supply in sevastopol. As a result, the city still fell to my rumanians, but it was a bloodier battle, and took until June 1, instead of May 20th. I may up it to 500 for the next game.
“My logisticians are a humorless lot … they know if my campaign fails, they are the first ones I will slay.” – Alexander the Great