The expedition came too late and with insufficient force to prevent the fall of Serbia and was complicated by the internal political crisis in Greece (the National Schism).

Eventually, a stable front was established, running from the Albanian Adriatic coast to the Struma River, pitting a multinational Allied force against the Bulgarian army, which was at various times bolstered with smaller units from the other Central Powers.

The Macedonian front remained stable, despite local actions, until the Allied offensive in September 1918 resulted in Bulgaria capitulating and the liberation of Serbia.

Following the assassination of the Crown Prince by a Bosnian Serb, Austria-Hungary had attacked Serbia in August 1914 but had failed to overcome Serbian resistance.

After the entry of the Ottoman Empire into the war on the side of the Central Powers (November 1914), the decisive factor in the Balkans became the attitude of Bulgaria.

The Bulgarian forces occupied Kumanovo, Štip, and Skopje and prevented the withdrawal of the Serbian army to the Greek border and Thessaloniki (Salonika).

The Entente used Greek neutrality as an excuse[citation needed], although they could have used the Albanian coast to rapidly deploy reinforcements and equipment during the first 14 months of the war.

The Entente was also delayed due to protracted through finally fruitless secret negotiations to bring Bulgaria into the Allied camp, which would have alleviated Serbia's need for Franco-British help.

With the Bulgarian breakthrough, the Serbian position became hopeless; their main army in the north faced either encirclement and forced surrender or retreat.

The Serbs faced great difficulties: terrible weather, poor roads and the need for the army to help the tens of thousands of civilians who retreated with them.

Only c. 125,000 Serbian soldiers reached the Adriatic coast and embarked on Italian transport ships that carried the army to Corfu and other Greek islands before it travelled on to Thessaloniki.

This advance gave some limited help to the retreating Serbian army, as the Bulgarians had to concentrate larger forces on their southern flank to deal with the threat, which led to the Battle of Krivolak (October–November 1915).

Despite the victory, the Allies managed to save a part of the Serbian army, while although battered, seriously reduced, and almost unarmed, escaped destruction and reorganized, resuming operations six months later.

The Allied armies entrenched around Thessaloniki, which became a huge fortified camp, earning themselves the mocking nickname "the Gardeners of Salonika".

[21] The Serbian army (now under the command of General Petar Bojović), after rest and refit on Corfu, was transported by the French to the Macedonian front.

[25] With the knowledge that Romania was about to join the Allied side, General Sarrail began preparations for an attack on the Bulgarian armies facing his forces.

Despite occasional local resistance from a few officers and their nucleus units, most of the troops, including their commander, surrendered to a token German force and were interned for the remainder of the war at Görlitz, Germany.

At the same time, the Italians had deployed more forces to Albania, which managed to push the Austrian corps back through very hilly country south of Lake Ostrovo.

Caftans, turbans, western suites in the latest style, black robes and scarlet fezzes like poppies" and Thessaloniki was "both wretched and splendid, just like the Orient".

[37] The mostly Irish troops in their letters to their families back home often described Bulgarians as "Brother Bulgar", and reserved all their hatred for the Germans and the British General Staff, which they accused of neglecting them.

[38] By spring 1917, General Sarrail's Allied Army of the Orient had been reinforced to 24 divisions, six French, six Serbian, seven British, one Italian, three Greek and two Russian brigades.

[41] Utilizing the cover of heavy artillery, a Franco-Hellenic force made a rapid push into the enemy trenches, conquering Skra and the surrounding system of fortifications.

A total of 1,782 soldiers of the Central Powers became prisoners of war, including a small number of German engineers and artillery specialists that served in Bulgarian units; considerable amounts of military equipment also fell into Allied hands.

On the Western Front, intense German spring offensives had not defeated France, and American deployment was increasingly effective, with US forces operating under independent command from June 1918.

Alongside its partners, Bulgaria continued to suffer high casualties and civilian privation, including food shortages, seemingly to achieve the unrealized objectives of its allies.

[48] However, the Austrian Empire was very much the junior partner in its alliance with Germany, and under strong German pressure Austria-Hungary had to continue the war, which caused serious morale problems in the Imperial and Royal Army by 1918.

Although a breakthrough was achieved at Dobro Pole and the Allied forces continued their advance, the Bulgarian army was not routed and managed an orderly retreat.

A mass of retreating Bulgarian mutineers had converged on the railway centre of Radomir in Bulgaria, 30 miles (48 km) from the capital city of Sofia.

"[54][55] On 29 September 1918, the German Supreme Army Command informed Wilhelm II and the Imperial Chancellor Count Georg von Hertling, that the military situation facing Germany was hopeless.

The British army headed east towards the European side of the Ottoman Empire as the French and Serbian forces continued north and liberated Serbia, Albania and Montenegro.