Faeelin
Banned
Some time in summer of 1942 seems likeliest. Situation after Kharkiv was quite bad. With Hitler dead and Germans offering some sort of reasonable terms? It might work. Stalin knows he can stay in power and is not going to try anything for atleast few years. With all of the Luftwaffe transferred to Europe, things in Mediterranean are going to get nasty.
Why would Stalin agree to surrender?