the royal air force carried out Action two bombing Attack raids Attack on sofia , the capital of bulgaria , in retaliation for the attacks Attack on yugoslavia , which ultimately surrendered Surrendering on 17 april .

at the same time , another ottoman army , ismail bey gathered Come_together in sofia , was about to cross Motion_directional in unk to invade Attack little wallachia , and connect Connect the two armies of the commander at bucharest .

when romanian troops approached the capital sofia , bulgaria asked Request for an armistice , resulting in the treaty of bucharest , in which bulgaria had to cede portions of its first balkan war gains to serbia , greece and romania .