Only Unity Saves the Serbs is a popular motto and slogan in Serbia and among Serbs, often used as a rallying call during times of national crisis and against foreign domination. The phrase is an interpretation of what is taken to be four Cyrillic letters for "S" on the Serbian cross. Popular mythology attributes the motto to Saint Sava, the founder of the Serbian Orthodox Church, however, the true author is Jovan Dragašević.

The Serbian cross, also known as the Firesteels, is one of national symbols of Serbia. It is present on the coat of arms and flag of Serbia. The cross is based on a tetragrammic cross emblem of the Palaiologos dynasty of the Byzantine Empire, with the difference in Serbian use being that the cross is usually white on a red background, rather than gold on a red background.