 The first phase consisted of a combined Franco-Serbian attack on the positions of the 2nd and 3rd Bulgarian Divisions, which was expected to create a breach of the frontline in the area of Dobro Pole, while also posing a danger to the Bulgarian supply lines on river Vardar.The Dobro Pole ("Good Field") peak dominated the region, providing excellent observation points for the defenders.Dobro Pole was surrounded by a well-developed system of trenches which, in combination with the rough terrain, made the area impassable for wheeled transport.