Preceding the main Russian army, Iosif Gurko led a detachment of 11,000 men to capture the vital Balkan Mountain passes.

The deciding moment of the Shipka campaign, and by extent the war, came in August 1877, when a group of 5,000 Bulgarian volunteers and 2,500 Russian troops repulsed an attack against the peak by a 30,000-strong Ottoman army.

On the morning of 19th July, while pretending to consider the terms of surrender, the Ottoman garrison slipped away to the west in small groups, leaving behind a large cache of explosives, ammunition, and artillery.

Süleyman loaded his 25,000 troops on transport ships at the Montenegrin port of Bar and sailed them through the Adriatic, around Morea, and then through the Aegean Sea and landed them at Dedeağaç, on the coast of Thrace.

[11] Some 15 battalions under Reouf Pasha joined Süleyman until his army reached about 30,000 Ottomans determined to retake the pass instead of simply bypassing it.

On August 23, the Ottoman forces attacked all Russian positions, with the main effort again at St. Nicholas where most of the defenders were Bulgarian volunteers.

[1] On the 26th, an Ottoman attack on St. Nicholas (a position referred to as "the Eagle's Nest") reached the Russian trenches but was repulsed again by a Bulgarian bayonet charge.

More Russian reinforcements arrived the same day and an attack was made against the Ottoman position but driven back to Central Hill.

General Fyodor Radetzky, now commanding the defenses, brought in reinforcements and a Russian counterattack drove the Ottoman forces from all captured ground.

Had the Ottomans been able to take the pass, they would have been in a position to threaten the supply lines of the Russian and Romanian forces in Northern Bulgaria, and organize an operation to relieve the major fortress at Pleven which was under siege at that time.

The war would have then been fought effectively only in northern Bulgaria from that point on, which would have led to a stalemate, which would have created a major advantage for the Ottoman Empire in peace negotiations.

The Bulgarian volunteers played a decisive role in defending the Shipka Pass, thus denying the Ottomans a major breakthrough and a chance to turn the tide of the war.

This strategic defensive victory illustrated their important role in the war and was dramatized by the Bulgarian poet and writer Ivan Vazov in his ode The Volunteers at Shipka.

The victory at Shipka Pass ensured the fall of the Pleven fortress on December 10 1877, and set the stage for the invasion of Thrace.

It allowed Russian forces under Gourko to crush Suleiman Pasha's army at the Battle of Philippopolis several days later and threaten Constantinople.