A ~ action is done only because there are no other ways left to achieve something or to prevent something happening. It is often done without much hope that it will succeed.
...a ~ attempt to prevent civil war.
ADJ: ADJ n
LAST-DITCH
Meaning of LAST-DITCH in English
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012