Franz's troubles were something Abdulmejid I could not understand, for if he had known Austria's plans, he would not have needed to abandon the Serbian region.
In fact, the territories that the Sultan Government relinquished were not limited to Serbia, but also included Bosnia and Herzegovina.
The reason was very pragmatic—they could not hold them.
Knowing they could not hold the territories, why should they waste their manpower needlessly? The Ottoman Government made what they believed to be the correct choice, concentrating superior forces to defend against the Russian onslaught.
As for Austria, after occupying Serbia and Bosnia, they found their battle lines overstretched, and they couldn't even secure their rear in time, let alone continue to advance.
England and France had already made promises to the Ottoman Government: as long as they defeated the Russians, they were confident that at the negotiation table, they could force Austria to relinquish all that it had swallowed.
