Your brave strike of Instambul was quite well. You've broken Turkish resistance, it has collapsed completely itself. You lost some naval ships. It's bad, but it won't be irreplaceable however could make your next operation easier.

!! For your knowledge !!:
In the next battle you must to seize, practically, the mountain fortress. It's sugested to reorganize the core forces. A lot of Mountain Infantry will be needed (they treat mountain hexes as a clear hex). A big number of Airplanes/Helos would be appreciated, also. Some vessels, too.