At the war's start, the Bulgarian
First Army was situated in north-western Bulgaria. Its advance into Serbian territory was successful between 22 and 25 June, but
Romania's unexpected intervention in the war and the Bulgarian Army's retreat from the front against
Greece forced the Bulgarian chief of staff to transfer most of the country's troops into the region of
Macedonia. During the retreat via the city of Ferdinand (now
Montana), a large part of the 9th infantry division mutinied and surrendered to the Romanians on 5 July. Consequently, only a small, mostly militia force remained to face the Serbian counteroffensive in the areas of
Belogradchik and Vidin. On 8 July, the garrison of Belogradchik was overrun by the advancing Serbs of the Timok group and a small portion of Bulgarian soldiers who had survived the Serb onslaught retreated to Vidin. The next day, the Serbs entered Belogradchik while their cavalry blocked the land connection to Vidin from the rest of Bulgaria. Near the village of Bela Rada, a bloody battle was fought between the Serbian advanced guard and a Bulgarian reconnaissance squad, which then had to retreat. ==Surrounding of Vidin by the Serbs==