It was a Battle of Many Nations
The Macedonian Front had one of the most diverse forces in the war. The Serbians were desperate for Allied help at the start of the war but the Allied forces had been consumed with fighting on the Western Front. Eventually the French and British sent two small forces to help the Serbians, but by then it was too late and they had already lost their country.
When the Allies decided to finally make a strong push on the Macedonian Front in 1918 more troops were dispatched from the Allies. The Italians, French, British, and Albanians sent forces. By the Battle of Dobre Polja, the Greeks had figured out which side of the war they wanted to be on. Therefore, Greece also sent troops to the Macedonian Front in order to defeat the Bulgarians and the Germans.
In total the breakdown of forces on the Allied side were 180,000 French troops, 140,000 Serbian, 135,000 Greek, 120,000 British, 42,000 Italian, and 2,000 Albanian. It was an incredibly diverse force that added up to 619,000 men ready to take on the brutal task of pushing back the Central Powers. Another aspect of the Allied forces that added to their diversity was that many of the troops sent by Britain and France were partially made up of their colonial forces.
The Central Powers were not as diverse as it was believed, and the Bulgarian forces were strong enough to hold the line. The 600,000 troops on the other side consisted mainly of Bulgarians, but there was the German 11th Army and some troops from Austria-Hungary. The fact that the bulk of the forces were from Bulgaria would be the deciding factor in how the Battle of Dobro Polje ended and how it affected the ending of World War I.