Original sentence: A day after the victory, the Bulgarian army prepared to attack the city of Niš, but the Austro-Hungarian delegation in the Bulgarian capital made it clear that if the Bulgarian advance continued, Austria-Hungary would have intervened in the war on the side of Serbia
Edited sentence: A day after the victory, the Bulgarian army prepared to attack the historic Serbian city of Niš, but the Austro-Hungarian delegation in the Bulgarian capital made it clear that if the Bulgarian advance continued, Austria-Hungary would have intervened in the war on the side of Serbia