It Took Months of Artillery Planning
With an uphill battle ahead of them and the Bulgarians in trenches hidden behind defenses and with the benefit of height, the Allies knew that artillery was going to be their only chance of success. There was no way to plan a surprise attack because there was no approach that would not be easily spotted by the Bulgarians. So the Allies planned to weaken the defenses and the morale of the defenders with an artillery barrage.
For four months before the offensive was set to begin, the Allies began planning for the massive artillery attack. They gathered together all the artillery that they could in order to have 553 guns ready all along the 15 kilometer stretch of the Macedonian Front that was the plan of attack for the Battle of Dobro Polje.
For every battery, they had four days worth of constant ammunition ready and waiting. More ammunition was waiting in nearby storage depots to be sent to the front at first notice. Two days before the infantry planned to move on the offensive, the artillery began firing. They had the goal to target the artillery of the other side and break down any fortifications and get into the trenches.
The hope was that days of raining artillery would give the infantry the advantage they needed to make it up the hill. The artillery did succeed in damaging the barbed wire that ran between the trenches of the Bulgarians. It was only one day of artillery barrage before the infantry felt that the wire and defenses were damaged enough to make a move.