The Battle of Maritsa, or Battle of Chernomen (Serbian: Marička bitka/ Маричка битка, Turkish: Çirmen Muharebesi, İkinci Meriç Muharebesi in tr. Second Battle of Maritsa) took place at the Maritsa River near the village of Chernomen (today Ormenio in Greece) on 26 September 1371 between Ottoman forces commanded by Lala Şahin Pasha and Evrenos, and Serbian forces commanded by King Vukašin Mrnjavčević and his brother Despot Jovan Uglješa, who also wanted to get revenge after the First Battle of Maritsa.
Before the Battle of Maritsa, Vukašin intended to recapture Skadar (now Shkodër) for the Serbian Empire. The army led by King Vukašin and his son Prince Marko approached Skadar in June 1371, but when they were informed about a large Ottoman army advancing from the east they headed east to prepare for the Battle of Maritsa.
The Christian army numbered 50,000-70,000 men. Despot Uglješa wanted to make a surprise attack on the Ottomans in their capital city, Edirne, while Murad I was in Asia Minor. The Ottoman army was much smaller, Byzantine Greek scholar Laonikos Chalkokondyles and other sources give the number of 800 men, but due to superior tactics, by conducting a night raid on the Christian camp, Şâhin Paşa was able to defeat the Christian army and kill King Vukašin and despot Uglješa. Thousands of Christians were killed, and thousands drowned in the Maritsa river when they tried to flee. After the battle, the Maritsa ran scarlet with blood.
Parts of Macedonia and Thrace fell under Ottoman power after this battle. The battle was a part of the Ottoman campaign to conquer the Balkans and was preceded by the Ottoman capturing of Sozopol in modern Bulgaria and succeeded by the capture of the cities of Drama, Kavála, and Serrai in modern Greece.
The battle preceded the later 1389 Battle of Kosovo, and was one of many in the Serbian-Turkish wars.