The Battle of Maritsa or Battle of Chernomen (also known as the Second Battle of Maritsa) (Маричка битка, битка при Черномен) took place at the Maritsa River near the village of Chernomen (today Ormenio in Greece) on September 26, 1371 between the forces of the Ottoman sultan Murad I's lieutenant Lala Şâhin Paşa and the Serbs (including their Bulgarian allies) numbering some 70,000 men under the command of the Serbian king of Prilep Vukašin Mrnjavčević and his brother despot Uglješa.
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, but due to superior tactics (night raid on the allied camp), Şâhin Paşa was able to defeat the Christian army and kill King Vukašin and despot Uglješa. Macedonia and parts of Greece 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 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, during which the Serbian forces were again annihilated, after which they would be unable to recover and would fall under Ottoman control. This battle marks beginning of long history of the Serbian-Turkish wars.